Two Things Edit

One: Now that the game is out, and we know that the church guy was, or at least claims to have been, bitten, we can determine that the infected do in fact bite. This would mean that infection is passed through bodily fluids, much like the Rage virus of 28 Days Later. Two: Can we safely assume that the green stuff that Bill rubs on himself is Boomer bile because if you look closely enough in the back round of that scene there is a dead boomer. --HarrisonH 07:43, 29 November 2008 (UTC)

That might explain why that horde of infected attacks them suddenly.I think the infected only bite those who are not immune or are dead.(Bill can be heard saying "If I go down,don't let those bastards eat me.")-- 18:57, 9 January 2009 (UTC)

Yes, The Infected CAN bite, as it was stated that The Hunter does bite their victims as well as pounce on them. Also, any Infected bile in this game is Boomer bile.Project Harbinger 16:45, May 4, 2010 (UTC)

True that he does say that,but most likely he is saying that because he is thinking stereo typical zombie(you haven't seen zombies eat anyone have you?-Gravhammer12 18:36 April 26 2009

One: I disagree w/the assumption we can take Church Guy at his word. We cannot.

  • A) He may have been bitten during the attack, but the bite is not definitively what caused the infection. He may also be lying about being bitten, or misremembering. He's not in his right mind when we encounter him.
  • B) IF this is a genetically modified strain of rabies, the fact rabies is transmitted via saliva does not necessarily mean that's how this Infection must be transmitted.
  • C) There are no observations that indicate the Infected eat at all. Seeking shelter, water, food, or a survival instinct of any kind are absent in their behavior. We never see them eat, much less bite the survivors, or one another.

Conclusion: The church guy's behavior is insane and erratic and undependable, and his eyewitness testimony to his own experiences are circumspect in that they don't measure up to observation. Point of comparison: The sheer absence of young and domesticated animals reveals more in what's not said, than the church guy's words reveal in what is said. Where did all the kids, dogs, and cats go? There's not even corpses of them anywhere. Discovering that would tell us more about how this disease behaves and perhaps even how it is contracted.

Two: The Boomer Bile may explain how some observations would lend credence to this being air-born and other observations seeming to contradict that. What if this Infection were air-born but only for short periods? What if the only way to contract it would be via Boomer Bile? Or perhaps to a lesser extent, when a Smoker detonates? Again, our Survivors are immune for currently unknown reasons (maybe they'd recently had their rabies shots?), but if every time a Boomer or Smoker explodes, any non Infected who inhale the air born bile would contract the disease. Said Boomer Bile might quickly lose its effectiveness after a short time exposure to the open air and the elements. Some could have come in contact with the Infected and not acquire the disease, unless a Boomer was involved. This would also explain perhaps where the children & domestic animals went. If prior to puberty, a human host body can only mutate into a Boomer, but some adults (or perhaps all eventually) can mutate into the other Special Infecteds, that would cause the disease to spread much quicker (within two weeks easy) especially since most parents wouldn't want to leave their child's side even after s/he began to show symptoms. The only thing I see that ruins this theory is the lack of reaction to all the children disappearing: no mention of it in the graffiti and no discussion of it among our Survivors. Perhaps they don't know, but one would imagine if all the children and small animals of the city exploded, there'd be some mention of it.

Of course, all this is mere speculation, but based more on observation than the presumption that biting is at all involved. We never see the Infected bite anyone. - ZachsMind 22:47, 19 March 2009 (UTC)

As aforementioned, Bill states not to "let these bastards eat me," and occaisionally, after being incapacitated and revived, Zoey will say, "I have tooth marks on me"

Waterga74 23:11, 20 March 2009 (UTC)

You certainly have some interesting theories there, mister. I, myself, think that the Infection is spread primarily through oral contact, saliva in specific, as it is a strain of hydrophobia. Also, as Waterga74 said, they talk about being eaten and bitten. The lack of oral contact is probably more to do with game mechanics than the actual nature of the Infection, as is the distinct lack of children—which I will touch on in a moment.
How do you think you'd work in the biting into the gameplay of Left 4 Dead? Would a zombie or two or three or more hold you down and try to bite you, and you'd have to press buttons really fast to get away (like in Resident Evil)? Would they just sort of casually nip at you while you're moving? What's the point of animating something you're probably not even going to notice, anyway? It's probably much easier to have them slash and smack and whatnot. Also, the zombies probably have to eat, maybe they eat their victims, but showing them eating when they're supposed to mercilessly barrel at you. Left 4 Dead isn't much for storytelling in front of your eyes, it's more of a story you have to read in between the lines to figure out, like looking at the graffiti. I think that's what helps to make Valve's games so...fascinating. I mean, look at the Half-Life series, and think about it.
Speaking of graffiti, have you seen the message a certain Will wrote? "TO HELEN LANE, DAD AND ME LOVE YOU AND WE ARE ALRITE - Will" It looks a lot like it was written by a child, doesn't it? I think the children are out there, but you don't see them in the game because that's basically a taboo in video games, it seems. You can't kill children.
I do like your ideas about how the Boomers and Smokers tie into it, though. Very well thought out. You most definitely bring some intriguing aspects onto the table. -§tigma-231 ¤here's a hole in my neighbourhood[talk][cont] 00:38, 21 March 2009 (UTC)

Since writing that silliness earlier in this thread some months ago, I now see that boomer bile can't be what causes the infection. Our survivors now run around carrying stuff and they throw it like a molotov. They'd have been infected themselves if that goo were responsible. If we observe the actual behavior of the infected, none of the animations show bite attacks. Regular and most Uncommon Infected usually just claw at the survivors. Hunter practically disembowels his victims but never eats them. Smoker uses his tongue tentacle, but then when he has you in melee range, he just hits you with his hands. Again he never actually chows down. The Charger may simply prefer tenderizing his meat before eating it, but he just pounds you into hamburger. Charger never actually dines. Furthermore, in Left 4 Dead 2 we now have Uncommon Infected in HAZMAT suits, and if you inspect them before they attack, you'll notice there is no indication that they have been bitten, or that the suit has been damaged in any way. This means either every person wearing a HAZMAT suit were infected BEFORE donning the suit, or that whatever causes the infection is not transferred by bodily fluids. If it's a Type A suit with its own air supply, we can rule out airborne transmission, and sometimes when you hit them, you'll hear the air going out of the suit. So. No bodily fluids. Not airborne. Whatever this infection is, it goes through HAZMAT suits. I can't think of anything of this world that would do that. That pretty much leaves either magic or alien tech. ZachsMind 02:33, December 8, 2009 (UTC)
Modified gamma rays? SilentShadow 17:26, January 3, 2010 (UTC)
First off, to the guy writing in italics. When you play left 4 dead, do you sit there watching zombies for 10 hours? No, you run up and shoot them. Thats expected, so even if you do sit there watching them for 10 hours, not seeing them eat isnt proof that they dont. Its just that the develepors didnt expect you to do that. Next, the bile and smoker spores are a viable meens of transmition. The survivors are immune. They will never become zombies. If the infected can tell if someone is immune, this could be a reason why they dont try to bite them. Its easier for a normal person to kill somone by punching and kicking than by biting.
not acctualy the infected was also eating human, if you didn't realize a splitted body with no guts (or intestine) in it and the other parts of the body dragged until fall from the office building on the street at l4d chapter3 map2-3(correction at 24th june 2011) Crazy al594 12:49, August 22, 2010 (UTC)
I have 2 things to say: 1. It seems that the zombies are just trying to hurt you anyway they can and they would probably bite you if they had the chance (for instance if you are holding their hands away from you it might attempt to bite you). and 2. I haven't read the whole thread, but someone said something about all the children disappearing, In real life their would probably be teenager infected but if a child about 4 or less gets infected they could die just from the infection itself and they might not become a zombie. The other reason that there are no children is that I think that they might not be able to sell the game if you are mass murdering child infected with all the gore etc. Just my opinion. LachlanR (talk) 20:53, November 6, 2012 (UTC)
Oh and also the person who was wondering how they would work biting into the game, It really wouldn't work because the same thing pretty much happens anyway when you get surrounded and it would make the game EXTREMELY difficult unless they made you have lots of health. I dont think it would work. And if they did a thing where you had to button mash to escape a Smoker, Hunter it would completely wreck the game because then teamwork wouldn't be needed as much. LachlanR (talk) 20:55, November 6, 2012 (UTC)

Cows Edit

It has been suggested here that cows may be the cause of the infection. Two reasons:

  1. In Blood Harvest, there are piles of dead cows. Their bodies seem to look odd, compared to our cows. Also, why would they be in piles?
  2. In the tunnel thing at the beginning of the finale of Dead Air, the signs say that you must contact security if you have been in contact with any livestock in the past 48 hours.

What are your thoughts? --HarrisonH 00:34, 2 December 2008 (UTC)

I think that the virus originated in cows, then thousands across the globe consumed the meat, only to mutate into the infected. Perhaps the pile of cows bodies was the armies attempt to kill off the virus in bovines, not realising it could spread through bite aswell? The DJ 14:54, 28 February 2009 (UTC)

Actually, since the infection is assumed to be a form of rabies, it would come to reason that animals are tested for rabies. This is generally done by testing brain tissue (which would, of course, kill the animal). With the extend of the infection the military probably killed all lifestock as a precaution and performed the tests to map where the virus had spread. We can not say for certain that the infection started with livestock, just that they were killed and tested as a precaution. -Tiger

Well one thing crosses out the idea that livestock began the infection because in The Hospital chapter of No Mercy, there is a room that has quarantine all over it,and if you go in there it has an X-Ray of the signature hand icon for L4D. Also, the piles of cows suggests that maybe aliens caused it.

...Wait, what? Sorry, but that really makes no sense. If it was caused by livestock, that means the products produced by livestock (such as meat or things like milk) may have carried the virus. The dead cows suggest that they slaughtered the rest of the livestock in hopes of quarantining the possible source of the Infection, to prevent others from being infected. The Infection is a mutated strain of the rabies virus—a disease which exists on Earth. Do you not understand evolution, my friend? -§tigma-231hаt i ɯill nəvər escaρe[łalk][ςont] 01:55, 27 April 2009 (UTC)

I think it is most likely to be a mutated form of mad cow disease, "mad human disease." The Deep 1 22:18, September 20, 2009 (UTC)

It couldn't be a mutated form of mad cow disease because that's not how MCD works. The disease doesn't cause the cow to become more aggressive, it causes it to act essentially drunk before the ungulate's legs experience paralysis. So, if the disease began affecting humans, people would act really drunk and then get paralyzed. Also, MCD is transmitted by infectious proteins, so that means transmission into other species is extremely difficult. And because it's a protein, it doesn't mutate, so it could never cause humans to become rabid.
Particularly since BSE (otherwise known as "mad cow disease") got its name because it makes an infected brain look like a sponge - it puts holes in brain tissue. Atypicaloracle 04:54, November 24, 2009 (UTC)

One possible dialog option in the sequel has the Survivors reacting to a large pile of dead cows in "Swamp Fever." Ellis reacts with surprise to the slaughtered and piled animals (which were not burned for some reason) to which Rochelle replies "They [CEDA perhaps?] say it spreads through mammals... maybe they're just being cautious?" Since the manual for the first game says the Infected have contracted a pathogen similar to rabies, and Mike Booth said that the game was meant to show a virus that "reprograms the behaviors of a complex animal – a mammal, in fact" it is safe to say that the Green Flu is some kind of super-rabies that just happens to have the T-Virus' ability to mutate people. Atypicaloracle 04:54, November 24, 2009 (UTC)

I think some CEDA scientists thought the disease might have come from cows, on the assumption that the infection might be spread through contaminated hamburger patties sold at a Burger Tank. However, after several veterinarian autopsies they came up with nothing substantial. It is curious that the game designers have gone out of their way not to include animals or small children among the active infected, but then they purposefully leave dead carcasses of cows for our survivors to observe. This is probably like the blood bags seen at Mercy Hospital which are all labeled "contaminated." That only means someone thought they were contaminated. That doesn't necessarily mean the infection itself is blood-related. It's just a logical conclusion any doctor might make given the circumstances. Now in Left 4 Dead 2, we witness piles of dead people who were obviously not infected at the time of their death. Some of the graffiti insinuates that these were "carriers" or whoever shot them dead in cold blood thought them carriers. At the end of L4D2 during the Bridge scenario, the military guys on the radio use the words "carrier" and "immune" in almost synonymous ways. They assume because our survivors are immune, that they must be carriers. We see the survivors get on the helicopter and we think they're flying away to safety. We thought the same regarding the foursome who ride off in a military tank at the end of L4D1. What we don't see happen after the credits roll is whether or not they live happily ever after. My guess is they are quarantined by the military. ZachsMind 02:44, December 8, 2009 (UTC)

Livestock might not have even carried the disease at any point, but since it mutates nearly daily, it is likely. Humans could have decided to try and eliminate any chance of being infected and thats why there are dead cows in piles. In Swamp Fever, there is a pile of dead cows with a fence around, and Rochelle sometimes states "We had a news report that Green Flu was spread by livestock" or something along those lines. LachlanR 09:04, June 17, 2012 (UTC)

Quick FYI Edit

According to the game's strategy guide,people been reported being sprayed with infected blood during combat and did not turn into zombies or show any signs of infection.It also says no one knows why the infection appeared,but it says that the zombies are not rising from graves.It also says that there is a large amount of false rumors about the infected and that CEDA is partially responsible for their circulation,but it's mostly the public spreading them.-- 23:58, 2 December 2008 (UTC)

It's plausible that the writers of the game do not themselves know for certain what the actual answer is, but left enough clues to suggest multiple possibilities, so fans could debate over it indefinitely. Hopefully though they made it a puzzle of sorts that can be sorted out with the evidence, and that there is an actual answer. Otherwise, debating over it would be futile, thus taking the fun out of such debate. However, as there is no evidence of aliens throughout the game, we can probably rule that one out. The fact the military actively efforts to save our Survivors at the end indicates they did not wish to leave them for dead. However, that alone doesn't fully remove "Government Conspiracy" from the table. It does indicate its unlikely. The gov't could have just as easily not rescued our foursome and just nuked PA from orbit. - ZachsMind 22:59, 19 March 2009 (UTC)

You shouldn't really take those strategy guides into context unless they're written by valve, and, unless you have a different one than I have seen, its not. Strategy guides can and usually are, total and complete bullcrap. Sure, its possible thats right, but almost certainly not. It, like other similar viruses, is airborne. How else could it spread to the entire state of Pennsylvania in two weeks, and all the way down to Louisiana in three?--Supermutantslayer450 22:35, September 16, 2009 (UTC)

Quoting some random dude that made some graffiti: "NOT AIRBORNE". However, you do got a point there, no other means of infection would make it spread so quickly, but let's take into consideration the Church guy wasn't immune, yet he didn't got infected until he was biten... DeathBlade182 02:09, September 17, 2009 (UTC)
More specifically, the Church Guy doesn't get infected until after our foursome approach him. Based on his own testimony, The Church Guy was bitten by someone who was infected. He says it happened an hour ago, and he hasn't changed. He may have thought it just an hour, but observation of his safe room indicates he'd been in there long enough to go crazy and write "better safe than sorry" a few thousand times in magic marker all over the walls. I'd say that'd take more than an hour to do. So maybe he did get bitten, but the bite isn't what made him change. It's not until the foursome get close to him and demand he let them in the safe room that he starts to change. That's rather convenient for dramatic purposes and we dismiss it as coinccidence, but what if it's a clue? What if the proximity of our 'immune' survivors is what triggers The Church Guy's transformation? Further, what if proximity to our survivors is what triggered the change of the copter pilot at Mercy Hospital's roof, causing Zoey to have to kill him at the start of Crash Course? Is there ever a time in either game when the survivors encounter another human being that doesn't change? Virgil from LFD2 comes to mind, but he may also be "an immune/a carrier." ZachsMind 02:52, December 8, 2009 (UTC)
Wasn't the Curch Guy so mad at the survivors? Maybe anger speeds up infection rate. Didn't the chopper pilot kinda get mad when the survivors took a little long? You gotta look into this. Nobody has mentioned Jimmy Gibbs Jr.. What about him? He probably got mad because no one got to meet and greet with him because of the closing of Liberty Mall. Very concerning. 03:53, May 18, 2010 (UTC)Guest

The Infection Edit

My theory for the infection is that it is directly related to cows and fast food. I think the cows were given something to increase production or something which in turn were sent to restuarants. Eaten directly by future boomers and common(did not eat as much). The virus creating special infected mutates from what the host has in their body(tank-perhaps steriods)(hunter-drugs)(boomer-ate hamburgers a lot, direct contact with the source of the infection)(smookers-chemicals in cigerates and cigars.) This is my second comment so I don't know if I did something wrong our what. sidenote-cows farmhouse finale thing or some other level(dont have game) are dead in piles and in dead air a poster says to contact security if u have been in contact with livestock in the past 48 hours. i dont firmly believe this but it sounds kind of logical. no theory on witch yet (please leave comments on this page) XboxBoxLiveGuy321 23:51, 12 December 2008 (UTC)

I laughed at the hunter's explanation. drugs? what? =P the boomer coming first makes sense, since it was the first special infected developed.

actually, I understood that the special infected were just mutations. for example, a boomer may have resulted as the virus affected the gastrointestinal system drastically.

All the infected have a special role against the survivors, aside from teh witch.. The virus may have just mutated into these to make sure that the remaining survivors were infected or at least killed, to protect its own life. Waterga74 22:59, 28 February 2009 (UTC)

My theory on the boomer is when a REALLY fat person gets infected, a hunter when a person on dope, pot, or crack is infected, a tank is when a REALLY strong dude is infected, and smoker when a smoker is infected. no theory on witch- 23:21, 13 April 2009 (UTC) Actually, the cause of thw witch is probably Depression or Long Term Sadness. This is probably why she is crying and wiping her eyes, and why she gets mad when someone gets near her

It actually sounds quite possible that a pharmaceutical company could be to blame by that reasoning. I mean think of how many items you use everyday that have some sort of chemical in it. You literally have to TRY to avoid them. Eveything has something in it. Perhaps a pharmaceutical company could have discovered a "wonder drug" used to increase the growth rate of things, kind of like a Fountain of Youth (Resident Evil-ish) and started mass producing it without proper testing. Farmers would use it on beef in the form of some ROIDS shots or fertilizer for tobacco.

  • The Boomers ate at McDonald's too much, and the substance had large amount of contact with the intestinal tract. This would explain the bloated, blob look and bile abilities as the substance altered the internal organs substantially.
  • The Smokers obviously are smokers, the substance would have a large amount of contact with the lungs and mouth. This would explain the altered tongue and coughing.
  • The Tanks could have got ahold of some of the ROID shots and used it directly, explaining the huge muscles as the substance did wonders on muscle growth.
  • The Hunters got some altered form of it cause it gave you a good high. Doesn't really explain the jumping and screaming, but they do look like thugs.
  • The Witches used another altered version for a weight loss pill, as the substance could be used for growth of organs that increased metabolism. Which as stereotypical as I can be, would help explain why all the Witches are young-ish, thin females.
  • The Common Infected just happened to get it from small everyday usage, not really altering particular parts, and they didn't get it in heavy dosages.

It would almost kind of explain the cows, and why they were killed. Though it does kind of open up a problem for the loads of pills all over the place, but then again we don't know the time frame of the entire attack, who says the Survivors aren't infected... Stoan04 14:05, 27 March 2009 (UTC)

In light of the new Smoker theories in L4D2, I kinda doubt he was an actual smoker in real life. Probably a tall person with a fungal infection that got overblown. Hunters might have been mutated by a strain of the virus which came from a dog or a wolf. EDIT: forgot my signature ^^; Deathhacker 21:37, December 2, 2009 (UTC)

What about the pain pills though? IF the medicine companies were to blame, why did the pain pills survive without a disease in it?

Maybe the hunters were methamphetamine addicts and the meth was made using pseudoephedrine-based meds that also contained the "wonder drug", that would explain their erratic behavior. 19:22, March 20, 2010 (UTC)

If special infected are caused by something involving the victem, and not the virus, why dont spitters, jockeys, and chargers show up in the first game?

Maybe This Is How The Infection Started? Edit

Obviously most people who play Left 4 Dead are wondering this. How the hell did the infection start?! Well, I think I might have an answer! The man who you see in Mercy Hospital behind the yellow Bio-Hazard tapes (Most likely donated by our very good friends, CEDA.) is most likely the origin of the infection. The infection must have started somehow, maybe it just came? Maybe it Evolved from another disease, such as Rabies. Well, this man went to hospital feeling ill. After they did some testing they found out he was carrying some sort of disease, but they couldn't tell which (As it was mutated!) so took him to a special care ward (That's why it's only one room, one bed at the end of a corridor near the top of the hospital: Where most real life special care wards are kept). Eventually he started to turn into a Zombie. Maybe when he was being tested on/operated on he bit a Nurse or Doctor, causing them to become infected. Eventually as more and more of them [Hospital Staff] became infected they started biting the patients, who in turn became infected. Eventually this spread out of the hospital and into the city/town. Then it just kept spreading, maybe some people got on a plane and set off for a holiday in the Bahamas, then that became infected and so on and on on. We know that within two weeks the military has tried [and failed rather epically] at containing the disease and just about everyone becomes infected. The survivors we know, are Immune to the infecte, as they might have a certain blood type, maybe better immune systems, maybe they can just reject the infection. We know the infection must have started in the North as when we start playing as Nick, Coach, Rochelle and Ellis in Left 4 Dead 2 we start in the south, which is new to the infection. The South, who know at dealing with the infection a bit better than the North, start bombing the hell out of New Orleans and many other cities/towns. This kills the infected, but alas also kills any people who are still alive/not infected. Going back to the North now. When you get to Dead Air you see the huge plane crash in an amazing fireball which would put a large Bonfire Night out of it's misery you wonder. Wait? If it crashed just now then mustn't that mean that the Pilot and Co-Pilot were still alive for a while, as I'm sure Infected can not fly an Airbus. Maybe there was one infected person on the plane, who infected all the passengers. The Pilots knew this and sealed themselves inside the cabin, hoping to land and leg it to safety (Inconsiderate bastards), but the pue number of infected on the door must have broke it, and the captain and co-pilot were either bitten or killed, so the plane crashed due to no one flying it. I also think that maybe the pilot knew everyone wa infected, but maybe though that the people in town were still alive, so he crashed the plane on purpose. If he did this then that man sacrificed himself to save a town [which was already overrun]. I think he deserves a medal. --WaffleMania 16:33, October 18, 2009 (UTC)

since there were almost no infected that came out of the crashed plane, I doubt, if any, infected were in the passenger compartments. It's likely the Pilot himself was infected, and turned while still airborne. When I played that level, I didn't see much in the way of corpses, meaning the pilot might have taken off with the plane empty, to save himself. Deathhacker 21:42, December 2, 2009 (UTC)

Quite the theory, I would follow along with that. Back to the airplane crash though. Shouldn't it be obvious as to why we didn't see any infected on that plane or bodys? Since the plane basically exploded im sure the bodies just burnt to ashes and what not, or they were just spread out evenly along the area. Or it could've been set on fire or something meaning they were just burnt to death. Who knows..-Zephusa. January 22, 2010

i think it fell out of the sky in a metor

I don't think something like a virus can survive out in space with no air/water/etc. Also, please sign your posts. TheDesertFox 12:14, March 13, 2010 (UTC)

Actually, it could. one popular theory right now is that life came to Earth on a meteor.

please sign your posts, also, I agree that It Is highly unlikely that a Virus could survive out In space 07:35, August 3, 2010 (UTC)

virus theory got a score, have you guys watch discovery channel?Crazy al594 12:55, August 22, 2010 (UTC)
(SPOILER WARNING) in the final mission of payday the heist you need to get 2 blood samples from a man in mercy hospital who is suffering from a "mysterious disease" as the level goes on he starts to look more and more like a smoker. so i think the infection started in mercy hospital. Orcaboy (talk) 19:54, February 6, 2013 (UTC)orcaboy
The hospital girl (Dr. Eriksson) in PAYDAY says several things about the right infected guy on the hospital room (they are random quotes), such as:
 "This man currently holds a weird and uncommon evolution of rabies"
"This man was in a trip to Haiti when during the flight back to the US he was shown with a bite that looked like of an rabid animal" (reference to this) - also, that's a fucked up movie, scared me for ages when i was 7
"He has signs of food infection" (probably the cow steak theory)
"This man came up on the hospital and attacked the doctors soon as he went to coma, he did not speak but only sounded like a dog barking, we think he is infected with rabies, as he works on a Zoo according with his indentification card"
Extra info: Chains says when he picks up blood from the guy "Shit!, this guy smells like a motha-fuckin monkey!, i can smell he is here on the ventilation shafts!"
Zombine™ (talk) 15:19, June 25, 2013 (UTC)ZombineTM - 25/06/13


Where are you guys getting the facts that the Infection is a virus, not a bactirium or Protist. Also, where is the rabies part coming from???

I'm pretty sure Valve themselves have confirmed it at some point. But, now that you've brought that up, I think we should probably start adding some references to things like that, just to make sure everything stays clear and legitimate. -§tigma-231hаt i ɯill nəvər escaρe[łalk][ςont] 02:08, 26 March 2009 (UTC)

Another question, where is the "Possible first infection" section in the article coming from?? this is speculation/opinion

Guys, sign your posts. TheCreaturenator16 19:15, 27 March 2009 (UTC)

Almost all of this is speculation and opinion.--Vaxnil

funny, i thought it was ebola virusCrazy al594 13:53, August 26, 2010 (UTC)

Mercy Hospital?Edit

I noticed this on a recent playthrough; the IV bags found near beds at Mercy Hospital all have "CONTAMINATED" stamped in big red letters across their front. While I am unsure of hospital procedure (maybe they stamp it as such as soon as they tap it, since it can't be used on a different patient), it seems suspicious that everybody in that ICU was getting fluid marked as contaminated. Raptor22 04:08, 31 December 2008 (UTC)

This behavior can easily be explained as a variant on the "Typhoid Mary" scenario. The hospital is overrun and there are many doctors and nurses doing everything they can in a crisis. One or more medical personnel notice a nearby blood bank is later reported to be overrun by Infected. Naturally they would assume that blood from said bank is also Infected, or at the very least compromised, and so they would mark that to separate it from the blood they still perceive to be good. Meanwhile, another one or more medical personnel, realizing they are rapidly running out of blood, would notice the "contaminated blood" and demand to know why its been marked thus, probably because there is a protocol to follow which due to time constraints the first group of medical personnel would have overlooked. The second group of medical personnel, ignorant or wary of the evidence the first group has regarding why such blood is presumably contaminated, would start using it anyway. This second group of medical personnel would be our "Typhoid Mary" group. They would perhaps be spreading the contagion, but refuse to believe any evidence contrary to their opinion. Point of fact, two weeks after contamination, there's still no evidence to suggest that blood is how the disease is transmitted. The second group may have been correct in saying the blood was fine, but they all died in a futile effort to save their patients anyway. Do remember there's a point in the hospital where we see an area cordoned off with yellow police tape. It's possible in that part of Mercy Hospital we might find the remains of "Patient Zero." - ZachsMind 23:32, 19 March 2009 (UTC)

iv bags Edit

i think that during the infection and realising that some people were infected meant that some of the blood people have donated had been infected and there were trying to keep the infected blood out of the system.I assume as soon as doctor realised that a blood pack had been infected blood in it they stamped the contaimated stamp on it to stop the same person blood being used on someone elses but due to the chaos and panic of try to figure out which blood packs they could still use they ended up.Or someone was testing the CONTAMINATED blood in the hospital and that it went wrong and overwelmed the hospital

--Spygon 09:44, 31 December 2008 (UTC)

Could have spread through livestock then infected humans which then spread through biting, blood, and saliva. 10:00, 31 December 2008 (UTC)

the date Edit

maybe this is not relevant for the infection but i read on the walls of many "safe rooms" R.I.P.s with the date on october-13-2009. maybe the infection started this day, on october 13.

also i read that the infection takes 5 min to 4 days to change you.

Okay, I realize that this was made a while ago, and this person didnt sign... but the blog on the l4d website says that the developing staff died in november. Maybe this has something to do with those deaths.. Waterga74 01:57, 18 March 2009 (UTC)

Seeing as the times taken to transform lower as time goes on (as each survivor writes an answer on the wall lower down), it is a possibility that The Infection continues to mutate, and is becoming more powerful/potent over time. -Bale, 06 June 2009

In the opening for L4D, Francis says "Merry Christmas", and in L4D2, sometimes when the safehouse door is closed, Nick says "Happy New Year" I think its taking place around that time.

Immunity Trivia Edit

I think there's a slight misunderstanding so far as speculation goes regarding the immunity of the survivors. All viruses, even those which are extremely common, are going to have people who are immune to them. Doctors are still actively researching why this is the case as they feel people who are immune may give us some idea as to how to get rid of such illnesses. But as it is, there are rare cases of people who are immune to Ebola hemorrhagic fever, AIDS, influenza, and so on. Something like this, that hits pandemic levels extremely quickly and changes people so drastically, would just stand to exemplify those with immunities.

That being said, the fact that the survivors are immune to it does not imply that it is a germ warfare agent, nor that a cure can be made any moreso than we can cure AIDS or the flu. (digiwombat | Not currently signed up) 22:06, 17 February 2009 (UTC)

That guy's smart. =O

But he's right. Viruses are just incredibly small organisms, smaller than germs. They alter the DNA of cells to produce more of the virus, which spread farther. This applies to all viruses. Some immune systems can, however, defend against them efficiently.

Waterga74 22:54, 28 February 2009 (UTC)

Viruses are germs too--User:TeriffiedToxic Life as we know it will end soon I think.. 08:43, 14 July 2009 (UTC)

As long as Valve still needs money, the Left 4 Dead world will exist with sequels forever and ever. ;D Zikkun 08:48, 14 July 2009 (UTC)

I'm working on a theory that one possible reason why Bill, Zoe, Louis & Francis are immune is because perhaps they have each relatively recently had standard rabies shots. We are led to believe that many people successfully took the route this foursome has. In fact, perhaps one or more of them helped orchestrate this string of safehouses and are now the last ones to run the gauntlet to safety. It's plausible that immunity can come from some small recent change to how rabies shots are done, and any adults in recent years who have had rabies shots would be immune. There may also be a number of immune people who didn't make it because they weren't capable of escaping due to lack of gun knowledge for example. This would not apply to childrens' rabies shots, which might help to explain why all the children obviously died off first. This theory however is dependent on yet another theory that the Infection is somehow artificially or naturally related to previous strains of the rabies (aka 'hydrophobia') virus. If it's not, then regarding immunity, I'm back at square one. - ZachsMind 23:58, 19 March 2009 (UTC)

That's kind of debatable of a theory. Since the classic rabies virus can only go from animal to human, but not human to human, this means that this has to be a mutated strain of that disease. And just because you were given the vaccine to one strain of the disease doesn't mean you're immune to them all. It's more likely that the immune have a sort of gene that protect them; like the sickle-celled anemia. If the survivors have one of the gene that case that, it means an infected blood cell will change shape and alert the white cells of it's presence,and the infected cell would be destroyed before the virus would be able to replicate itself. But of course, that only works if the virus causes the cell's Ph-level to change.

Waterga74, viruses are technicly "Germs" because the definition of a germ is a microorganism that causes diseise. --Djj51 02:52, 20 April 2009 (UTC)

Not all viruses cause disease, as many viruses reproduce without causing any obvious harm to the infected organism. Some viruses such as hepatitis B can cause life-long or chronic infections, and the viruses continue to replicate in the body despite the hosts' defence mechanisms. Taken straight from . Stoan04 14:14, 27 March 2009 (UTC)

Stoan, what you are saying is correct, but that is not what I ment. Waterga stated that viruses were smaller that germs and some viruses are germs (disiese causing organisms) --Djj51 03:14, 30 March 2009 (UTC)

Technically, are viruses even considered living things? Since all they have are a protein coat, the RNA and whatnot, and the flagella on some to help move around. Other than that, there are no organelles or nuclei. (This is Blacklite, by the way.) 12:23, 30 March 2009 (UTC)

I would assume Viruses are considered living as much as our own cells are, or even sperm, which I would assume are basically the same size (and do basically the same thing...). Stoan04 15:25, 30 March 2009 (UTC)

From Wikipedia:

"Opinions differ on whether viruses are a form of life, or organic structures that interact with living organisms. They have been described as "organisms at the edge of life", since they resemble organisms in that they possess genes and evolve by natural selection, and reproduce by creating multiple copies of themselves through self-assembly. However, although they have genes, they do not have a cellular structure, which is often seen as the basic unit of life."

I honestly think that viruses aren't living things, and just micro-organic vectors that solely spread disease and nothing else.BlackliteWrath 12:36, 14 April 2009 (UTC)

Some microbiologists classify viruses as nonliving, because all they are is a string of DNA and a protein coat, and that they don't fit into any of the seven kingdoms. But, then others say they are living due to their infectious manner.--Djj51 02:52, 20 April 2009 (UTC)

This is a heated debate! x3 Anyways, whether or not a Virus is a living thing is up to your own definition. Scientifically, Living things are made up of at least one cell. There are also variations on that, such as whether or not a tree is alive. Trees grow and rot, but some people would not consider them "alive" because they have no sentience, no consciousness, no brain. Viruses are not made up of cells, nor do they have what appears to be any form of intelligence. They're like a program, designed to perform that task meaninglessly until they are destroyed. A more natural analogy would be the stars in the universe: they come into existance, expand, explode and form new stars, but they're clearly not alive.

On the subject of Immunity, there will always be a select group of a species to be immune to something. This is due to a slight mutation in their gene. When a crisis comes (be it a virus, a natural disaster, or some other equally genocidal act of god) those with the right mutations will live through and, being the only remaining members of their species, reproduce and preserve the mutation forever in the new genepool. This does have problems tho, since usually if the group is immune to something, chances are they're also all equally vulnerable to something else, which is why inbreeding in humans (i.e: making love with your sister or cousin) is looked down upon, since you are effectively doubling your children/nieces' chances at being vulnerable to something trivial. Humans do perform selective breeding, for farming, science, and pets (ever see a natural Siamese fighting fish? it looks nothing like the ones in the store). Those common White mushrooms were based entirely in a mutated patch that a farmer thought would be nice as a novelty food, and now it's one of the more popular mushrooms. Deathhacker 01:32, January 27, 2010 (UTC)

Pathogens: Comparing fact to fiction Edit

One point that I have not noticed anyone else make is that this is no ordinary pathogen. Viruses like AIDS and rabies and ebola damage tissue and even affect on a rudimentary level some behavior patterns among the infected. Particularly rabies with the latter, and ebola with the former. AIDS only seems to attack the immune system of its host, making the host more susceptible to other pathogens. In other words, AIDS appears to specifically target its host not to kill it, but to allow the host to be killed. This is counter intuitive to a survival instinct of more advanced living things. Viruses that we know about tend to purposefully endanger the future of the host, therefore limiting its own future as well. There's no survival instinct. However, the host him or herself is still cognizant the entire time up until death and actively in most cases persuing avenues of departure from its own demise.

This Infection removes from its host the will to live, and the will to allow anything else live. It appears systematically designed to decimate the human race. This Infection isn't just targetting the immune system or the digestive system or causing discomfort that leads to erratic behavior. This Infection affects the very nervous system of the hosts, turning them into agents for its own demise and that of its target. The thought of it is actually rather fascinating. ...well if it weren't so creepy it'd be fascinating. - ZachsMind 23:47, 19 March 2009 (UTC)

Well, heck, he's got us screwed. Waterga74 23:08, 20 March 2009 (UTC)

I noticed this as well. Consider how well-adapted the special infected are to their given roles, especially the Boomer. A pheromone like Boomer bile can certainly evolve in nature (ants and bees have similar "kill this thing" pheromones, although they don't have horde-summoning powers), but it would take a very long time. Hundreds of thousands of generations, at least. Something like that could not evolve overnight. Furthermore, for very many Special Infected to have the exact same mutant strain, the virus can't be randomly mutating DNA on an individual level, or it would get very many different results. For the Infection to be even a little bit realistic, it would have to be created by some kind of intelligence. Is it man-made? Alien? Is it a self-aware virus with a hive mind of sorts that can intelligently mold its victims? Is it just a video game? Am I overthinking this? (yes) -Virusbomb 02:27, December 15, 2009 (UTC)
The virus could induce rage in the victims as a side effect. It's mentioned that the virus removes the ability to eat and sleep from the host. I've went 24 hours once without food or sleep (but with water). trust me, it aint a pleasant experience. It could have just simply removed the mental ability to perform such acts, and the resultant starvation caused the rest (brittle bone and muscle structure due to starvation and lack of nurishment, rage due to sleep deprivation, etc...). as for the SI.....well I'm stumped there. Deathhacker 02:48, January 27, 2010 (UTC)
It might even be possible that the infection is somewhat intelligent, although in a loose sense of the word. Consider that the objective of the infection is to reproduce. A host that is kept living can constantly produce new cells. The common infected, and also possible the boomer and smoker, would serve as the main agents for the infection of the population. However, there is a problem. Some people are immune to the infection. And they are pissed off about there friends being turned into zombies. In this respect, the infeced now form an army. The common infected serve as the backbone of the force. There are so many that the infection can afford to lose them. The special infected are sort of like special forces. The boomer allows for more coordinated attacks by the common infected. The smoker, charger, jocky, and even to some extent, the spitter, sepperate normally powerful teams of survivors. The hunter picks off lone survivers easily, and can also do some damage by simply rushing in and meleeing like a normal zombie (although this is a player tactic in versus, and is never used by the AI). The tank exists purly to destroy. That much is obvious. But, consider, that it is so strong, it could be used for more than just killing people. What if there are a bunch of people holed up in some sort of fort. Normal zombies might not pose too much of a threat, but even a well set up fort is vulirable to cars being thrown at it. The tank smashes a hole in the defensis, and the rest of the zombies rush in. Then there is the witch. Gameplay wise, she makes sence, but not story wise. In reality, she wouldnt seem to serve much of a purpous. However, in L4D2, they are explored a little more, and it is revealed that they are atracted to sugar. What if the infection requires abnormal levels of surgar to reproduce. The witch wanders during the day, Eventually, it finds a source of sugar and stays there. Its cries attract other infected, allowing them access to the sugar. Its strength would allow it to defend itself, and its stach of sugar, from anything that would attempt to take it. This also offers a plausable reason for the common infected to be attracted to loud noises.---Vaxnil

Special Infected Edit

I believe that the infeced have changed more along the way, or the virus is still taking its course. At the begining of the game, Bill says that the infected are "changing", when Zoey and Bill see the Witch, they had no clue what she was...because they had never encountered her before. Now after two weeks, they surely must have seen a Witch at least once. This leaves two possible conclusions:

--A: All 4 of the survivors have been living under a rock.

--B: The infected are changing and/or adapting.

Once the game startes, they have established nick names for the infected from what they have seen, and how they act. A scarey thing about this is, after two weeks this is what the infected have adapted to, after two MORE weeks, there will be more infected that have converted, and possibly new types of infected. Imagine, all of the normal and common infected are now all special infected, no "plain" zombies...The world of L4D would end quickly. It appears that for the infected to become "special infected" it takes time, such as first meeting them after two weeks (which would mean, it took the original zombies 2 weeks to change to this), which would mean, the special infected that they are fighting now, were the first to fall to the virus. However, time to become an infected could vary between others, such as how some fall to the virus in seconds, some in days while others are immune. Example, the "Church Guy" became infected an hour after he was first bit, therefore, it took him a short while to become a special infected. While others, who become zombies days after they were first bit, may become special infected days after they become a zombie. --User:Monobrow1

your logic to them "adapting" is logical, however, I had assumed that they were just mutations among the ordinary infection, causing strange appearances and "growths." As you said, the church guy transformed in like, and hour to a special infected. So yea. I'm sticking with "mutations." Waterga74 14:22, 23 March 2009 (UTC)

Mutations of the infection is probably the best way to explain the Specials. I mean as Waterga pointed out, Churchguy turned into a Special within an hour. But both of you could be correct, the Infection as pointed out numerous times is not normal. As with other things, viruses and bacteria are going to do different things to different people. It could take a while for the Infection to overcome your Immune System completely leaving you as a Common until it did, and afterwards it turns you into a Special. Or you could have a weak immune system, due to Pneumonia or HIV/AIDs, allowing the Infection to get started and get done quickly. So depending on how your immune system is, it could take weeks, days, hours, minutes to turn you. Even the graffiti on the walls shows it could take different amount of times. Or mayhaps, the virus is adapting and becoming stronger. Stoan04 14:24, 27 March 2009 (UTC)

I think the special infected came to be because they have survived longer than regular zombies. Regular zombies only survive a couple days, while special infected have changed over alot of days. So if a regular zombie stayed alive long enough, they may turn into a special infected. Camster103 22:10, October 21, 2009 (UTC)

The Church Guy kinda disproves this. He will always turn into a special infected (although not a Tank or a Witch), meaning that mutation takes hold immediately. Since he was speaking coherently (albeit insanely) before, he must have just turned.

I think that the specials came about from slight mutations from the original virus. This seems fairly possible since some viruses can mutate quickly, like the flu. This would result in more than one strain of virus. Also, the new specials in L4D 2 appear to be mutations off the original type of that zombie, i.e. spitter=mutant boomer, jockey=mutant hunter and so on--Djj51 22:45, November 8, 2009 (UTC)

I think that when the infecion finds the proper host it starts mutating. Common infected will remain like that and wont mutate. Exampe: When the infection finds great agility in the host he wll became a hunter. When it finds great strengh in the host he will turn into a tank. But I dont know how the newest infected (charger, spitter) were find to be ¨suitable¨ to mutate. Maybe the infection has now several different straits that transform the host into something no matter what he is.KarmaChargerIsAlwaysWatching 15:27, April 25, 2010 (UTC)

Nononono, a common doesn't turn into a speial after some time because they DIE! I have to admit that I haven't seen it myself, but i read on this wiki that when you watch a common long enough, they fall over and are dead without being harmed! Just like they vomit, fight and so on this is just one of many common animations. I think only people with special attributes turn into special in fected (obeese people = Boomers; people bound to wheelchair = jockey; Bodybuilders = Tanks and so on) this is also plausible because when you walk out on the street, you see much more obeese people or chain smokers than bodybuilders or people in a wheelchair. Same thing in L4D. So church guy was either obeese, a chain smoker or did parcour (?) since he will immediately turn into a boomer, smoker or Hunter. DasBeda (No account and sry if my english is not correct) 3:06 MET, 5 September 2010


I believe bugs are immune,as you see a fly in the intro movie,unnafected by what it`s eating.Bigens 23:39, 4 April 2009 (UTC)

Well that says nothing about what is immune, I opt to change the name to insects, anyones opinion. --Djj51 03:00, 20 April 2009 (UTC)

There.Bigens 03:12, 20 April 2009 (UTC)

I think that if there WERE infected Insects in the game, wouldn't there be some sign of them being infected? Such as the insects swarming around the Survivors, even being harmless at best. But then again, that would be too annoying for the players and the programmers. But then again again, there should be some signs outside of affected the Survivors that insects are infected. BlackliteWrath 11:53, 20 April 2009 (UTC)

Yes, but insects are so far away geneticly from us that they would be unaffected, the only other animals that might get infected are pigs, monkeys, and apes --Djj51 21:50, 26 April 2009 (UTC)

Do we know how far away from Humans an animal would have to be to be unaffected? Fadm tyler 14:16, November 4, 2009 (UTC)

Yes, but since we all share the same DNA bases, and cell types the infection could infect flys and insects, but due to the fly's short life span, it wouldn't make a difference. Larger animals, more specifically vertabrates, could be affected more visibly. --Djj51 20:15, November 7, 2009 (UTC)

But, I would expect that all animals affected by this virus would die. If there were infected animals, I would've expected them to have been at least shown somehow, or put in-game. I believe that all animals affected by the virus would eventually die from it. -Charger09 5:33 Nov. 8 2009

What about the Bubonic Plague? It was the fleas on the rats that came from Asia that spread it to all of Europe, effectively wiping a third of it. The flies/cockroaches/crickets in the game could simply be carriers themselves. Insects have tons of diseases that they themselves are immune to, but other animals (such as ourselves) can be extremely vulnerable to. - User:SAmaster01


do to the 4 areas that the game takes place in, it is possible that the Infection could only afflict the Eastern coast of america. --Djj51 21:15, 17 April 2009 (UTC)

Indeed, but judging by how hard it seems to be to find a safe place from the Infection, and how illnesses like to spread around like wildfire, chances are it's spread to other regions of North America, maybe even beyond that. Maybe somebody who got infected, but didn't know it at the time, boarded a plane to the other side of the world. It only takes one person to spark a flame. -§tigma-231hаt i ɯill nəvər escaρe[łalk][ςont] 05:19, 18 April 2009 (UTC)
How do we know this infection started in america? If what some people are saying here could be true the infection could have traveled on a plane from anywhere in the world (yes air travel is possible, since there were claims in the grafitti that it took upto four days to transform). But, it is also possible that in that country, this person who traveled to pennsylvania was the only one infected in his/her country. - Gogolo30 6:58, January 25, 2010

I agree with stigma as i feel the situation is either like the 28 days later way where the whole of the usa is infected but the other countries have quarantined the united states or the more likely situation where the infection is worldwide as it seems to have spread so quickly in 2 weeks and theres no sign of any other nations trying to help out the areas.Spygon 12:46, 18 April 2009 (UTC)

Yes, but in only two weeks, the tree cities and the forest where overrun, on the assumpsion that the infection started in one of the cities, it is possible that the airports where quickly quarantined, and the military set up rescue areas. why would they do so if there was no place to go to in the end, think of the movie I Am Legend, in the begining, he acts like he is the last one left, but later on new people are introduced, and an entire colony of people is still alive. this transfers to left 4 dead in the way that a highly infecuous diesise has trouble spreading due to a tiny fraction of the overall population of an area. If 50-75% of all survivors escaped the areas of left 4 dead, then they could just go the couple THOUSAND miles across the U.S. and find that life is unchanged there --Djj51 18:33, 18 April 2009 (UTC)

but thats the thing with i am legend the people that are found are other survivors and the camp is a camp full of survivors the army show no sign of being around as i feel this would be the same in the world of left 4 dead as there would be small groups of survivors hanging on by there finger nails.As we know that during the first 2 weeks of the infection the army have been on the back foot and everytime they have tried to control the outbreak they end up being overrun so as the way it has deverstated and infected at least 95% of the areas population i would feel that is has spread like wildfire across the country at least.Also with how many infected and corpses around i doubt that 50% managed to escape to be honest at the very most your looking at 10% of survivors getting out of the area.So with how many people are in close proximity to each other the infection would spread through most areas of the usa stupidly quickly.Spygon 09:23, 20 April 2009 (UTC)

On this subject, we can be sure that there are small groups of Survivors are still alive. In No Mercy, machine gun fire can be heard in the distance. The spread of the Infection, however, leads me to believe that most of the large cities on the East Coast have been overrun, and depending on the response time of the military, aircraft could have taken off and infected cities around the country; maybe even the globe! Where did the plane in Dead Air come from? There has to be military installations somewhere, where they have been able to hold out. Piranha Talk to Me Demon Razgriz Logo 21:23, 8 May 2009 (UTC)
If you check the map in the Finale of Blood Harvest in the farmhouse by the radio, at the top there is a section marked "Safe Zone". This is the "Military safe zone up north" that the helicopter pilot referred in the cut sound files. You'll notice it is a rather large safe zone, looking down and comparing them with Riverside, Fairfield or Newburg. That is most likely where this "military installation where they have been able to hold out" that you asked about is located. --Five Dog(Talk) {Updates} 16:34, 31 May 2009 (UTC)

Well,part of this theory just got torn to shreds, due to parts of L4D2 being in New Orleans --Djj51 13:46, 6 June 2009 (UTC)

Yes, but this happens about a week after left 4 dead (correct me if im wrong) and the first campaign of L4D2 is set in savanah where the infection is just gettin to, meaning the infection has been less destructive the originally thought. as the south is only just getting infected 3 weeks after the first infection, that means that the infection was quarintined much more effectivly than thought in the north, so the rest of the world might be just getting hit, if its even spread outside the US. --Just Some Guy720 15:34, October 10, 2009 (UTC)

So, in theory, one more week and we have the infection in the midwest. But by this time the military will have learned how to stop the infection from moving as fast, so one week from then it would have spread completely around the U.S. --Djj51 22:38, November 8, 2009 (UTC)

Animals and ChildrenEdit

I am going to attempt to explain why there are no infected animals or children in the game in both practical and game-canon perspectives. The children and the elderly are probably just killed by the infection rather than mutated. Also, shooting children and old people would probably just detract from the game, not to mention get complaints. Animals may be immune, because you can hear dogs barking in the distance, not to mention the rats that can be heard and the crows in Blood Harvest. The dead cows were probably killed by humans, because why else would they be stacked in piles? From a practical perspective, animals would be hard to incorporate into the game. Also, they would be annoying. That is one thing that was annoying in Resident Evil: zombie dogs. They did nothing but annoy me. TheCreaturenator16 05:10, 13 July 2009 (UTC)

I have to agree, Valve did so to avoid getting complains seems explainable. Take a look at Resident Evil 5, most players just call Capcom racists now. Animals' might be hard to answer on the developers' side, but I guess that the virus that turns people into Infected just doesn't effect animals if you put it canon-wise. The cows are really odd in my opinion, other animals are not seen, there is a sign in Blood Harvest that said "Deers in the way", this could mean that most of the animals just tried to run-away because we don't see them. I think it's just Valve's doing, they also removed all the Children in Half-Life 2 not to make references such as the Ghetto, and so they did so in all their games. Zikkun 06:11, 13 July 2009 (UTC)

Also because it's apparently wrong to kill children in video games. I can't think of any game where it's allowed... But that's also partially because PETA would make Valve become an hero with their incessant whining after, I'm sure.
Now that you mention that, I barely recall deaths of children in video games. Well... I remember killing 2 years ago a kid in RollerCoaster Tycoon 2 by mistake because my ride was epicly bugged, can I sue Atari?>.> The children are understandable, but why animals? Valve's Headcrabs somehow count as animals in my book. Zikkun 08:37, 14 July 2009 (UTC)
Like that fly. -§tigma-231oƒ my caliber {τalk}{¢ont} 20:40, 13 July 2009 (UTC)
Oh, that's another thing. Totally off topic, but come on, who hasn't smacked a fly? I support a lot of PETA's views, but some are just out of hand. But I digress. TheCreaturenator16 06:41, 14 July 2009 (UTC)

In Fable 2, Rose got killed at the beginning of the game, and that was up close. On Fallout 3, if u decide to blow up Megaton, you will kill 2 kids. Fallout 1 and 2, you can kill kids, but the company doesnt really want you to, and killing 1 child has more severe consequences than murdering an entire town.--Supermutantslayer450 22:28, September 20, 2009 (UTC)

Let's not forget Little Sisters O.O Oh and in Resident Evil...4 I beileve you can kill the girl you are protecting or just let her get killed...And staying in the Fallout 3 topic... They won't let you kill kids, no matter how much you hit or shoot them, they are invincible.

Elite-Nachos 04:55, October 25, 2009 (UTC)

Yeah, but if you blow up Megaton, two kids are in there,they dont get out, and theres no way anyone can survive a neclear explosion if they are right next to it.--The Scat Man450 ROAR! 16:26, October 25, 2009 (UTC)

I was just gonna say Bioshock. And I'm pretty sure I can pwn a kid if I were to rape Stormwind in WoWDisMEMBAH 18:36, April 27, 2010 (UTC)

Rabies Edit

i have readed many threads that say that it has been confirmed that the infection is mutated rabie...but why cant i find the original post, can YOU link it? Gesmana 05:58, 30 July 2009 (UTC)

The Hunter - The only infected to bite in-game? Edit

I was going through the hunter's model animations the other day, and found somthing of note: The hunter bites people it pounces. or at least it appears to, leaning down to roughly the target's neck area, with a Gore splattering sound playing upon "contact". Can anyone else check this using the left 4 dead authoring tools beta? There's normally too much else going on to spot it in-game. I'm not sure myself, but I beleive it warrants discussion. --AstralShapeShifter 22:21, 3 August 2009 (UTC)

Indeed it does bite. I checked it out myself in the SDK. Darkman 4 00:56, September 9, 2009 (UTC)
...Now someone thinks it's the rage virus... can we have a fact check here? I never said anything to the effect of hunters infecting people. If it was only hunters, christ, noone would be infected.(the hunters turned up 2 weeks after first infection)--AstralShapeShifter 10:12, December 13, 2009 (UTC)

Possible origin for the witch Edit

as we have defined in the talk above, the virus affects different people in defferent ways. seeing as there are common women infected, we have to assume that there is somthing different about the witch. Is it possible that the witch might have been a woman who had a personailty disorder before the virus?

Not a personality disorder, the Infection apparently destroys most higher brain functions, so this wouldn't affect the person. perhaps the witch was once a person who took slimming drugs because they thought they where fat. The drugs could interact with the virus to create the witch. The witch crying is probably a tactic to draw in the survivors.--Djj51 17:14, October 1, 2009 (UTC)

Thats quite possible, but its also possible that the witch could be what happens when the tank strain infects a woman. think about it: witch and tank are both strong as all hell (the witch is actually stronger then a tank) both have higher health then all other then infected and both are moody as crap ( witch goes from sad to angry to coward in 3 seconds if playing on expert and i aint never seen a happy tank. you guys?) also she could have much more devloped legs then the tank seeing as shes faster then him, and the survivors, instead of the bullet immunity and concrete detector the tank has. or this could all be incoherent babble cuase im pretty tired :) --Just Some Guy720 15:28, October 10, 2009 (UTC)

Tanks seem perfectly happy to be whooping my backside all over the place or one-shot-killing me off the top of the hospital or trying to drown me in a swamp. Things love their work. Atypicaloracle 04:43, November 24, 2009 (UTC)

Its agreeable with the slimming pills thing, another reason why she cries probably, if you see people who hate being "Fat" in their terms, they aint gonna be happy happy about it, they are gonna be misserable and upset about their weight, and the fact they get angry when they are Bothered, you aint exactly gonna be like oh its alright for putting a bullet in my eye (Whilst crying) it would be like for god sake LEAVE ME ALONE! and the cowardness part could be oh i cant be bothered with you. Off track there, an origin for the witch, tracking back to the Disorder part, she could have had a depression disorder, and maybe the virus didnt wipe out some parts of the brain and took the depression part for granted, also depression could lead to forcing yourself to be sick (For some people i know) whilst human, she could have done that, leading to her slim figure, and i havent seen a male worry about their weight to be honest. Whilst losing figure etc. An infected could have bit her possibly from the family, and the infection could have been in early stages, so it didnt wipe total function of the brain but took a key part for granted and evolved it to what we see as the witch.

I have my opinion on the Witch, rather than her origin, but a theory of why she cries, and leaves after killing her target. Well, seeing as the Witch cries, I would think that she is aware of her current state as an infected. This causes her to cry, because anyone who turns into a monster I would think would be emensly sad. But she cries uncontrolably, never stopping, day and night. I would think the virus has uses the crying as a lure (Proven by Zoey mistaking the Witch for a survivor), although the Witch doesn't mean it to be. As for being startled, she has a rage similar to the tank, as it gets out of control when it spots the survivors (Maybe the strain of infection is similar?). She then kills her prey, but you notice that she looks as if she had no idea what was going on, and runs away, holding her handsto her face. I think this means in her rage, she blacks out, and the rage controls her. But after she kills her target, realizing what she had just done, she runs away, as if she is trying to leave as to not cause more damage than she already has. Then sometimes she will strike at the others, but only as a means of getting them out of their way. She is unaware, yet aware of what she can do, and that is another reason she cries I would say, as her claws are already red, meaning she's killed before, and knows the things she's done, the people she killed. -Charger09 5:47 Nov.8 2009

stress, trauma, a mental moron, drug addicted, witch is the only one with stress, trauma, and too much drugs and burgersCrazy al594 13:19, August 22, 2010 (UTC)

Witches are atracted to sugar. Maybe the virus needs a lot of sugar to reproduce, and the witches act as becons/guards.

Carriers Edit

Hi, would probably be good for someone to add in a section about those with Immunity to the infection still being able to carry the infection. This can be assumed from the graffiti in Left 4 Dead 2 in the various safehouses...

One thing I noticed playing through the Parish earlier; in the Cemetery level, not too far after leaving the safe house (can't remember where exactly, but it was inside one of the houses you have to go through I think. I'll check in the morning), there's some Graffiti where the writers are saying that the military has abandoned them, and other things along those lines. One possibility is that while some people were killed who had the Infection and were going to turn (hence the piles of bodies outside the trailer who "aren't zombies"). The carriers, however aren't killed initially; there's graffiti discussing why certain people are being shipped out immediately. The carriers are basically abandoned within the quarantine zones, left to be killed by the infected (but not killed outright by the military). I'm not sure why the military didn't simply kill the carriers, as the public sentiment seems to be for their demise, and it would be much simpler. Perhaps the military didn't want to cause a possible controversy? I'll look into things more later when I'm not so tired. -- 09:13, November 19, 2009 (UTC)

All this is entirely confusing, especially after Papa Gator asks if you're immmune, and after you say yes, he refers to you as a carrier and rescues you. Maybe the military switched tactics and realized carriers are the only ones that are able to be saved (and may be one himself?) Edit: It probably gives insight to the amount of carriers there are in the population. The military by the end of L4D2 still seems well armed enough to have a force of pilots and ground troops (who are more than likely immune). Thinking about it, they were in a much better position to kill the infected and save those amongst them that were immune - a lot of immune civilians simply died outright, as shown in multiple places. Immune soldiers, however, would have little problem grouping up. DShadow 18:09, November 19, 2009 (UTC)

Infection theory Edit

Hasn't anybody noticed that the 3 new infected look like they have some other diseases, like the Jockey and Krypsiosis(or whatever it's called). I think it's because the Infection is somehow crossbreeding with other, entirely different diseases. I know it'd be impossible in real life, but still: It's a videogame: Everything is possible.Mr.shadow 09:42, November 11, 2009 (UTC)

I have an idea about the infection. It could be that the goverment was working on some sort of gene changing program, using a virus as a base to cause the changes. If this is true, then the virus could have shared genes with the rabies virus.

I have an idea about the infection. It could have been a retrovirus mutated the X-Chromosone somehow, and since everyone has an X chromosone, everyone's at risk. It would also explain why there are more male survivors than female, because females have two X chromosones which means they are at higher risk of infection. If it was a mutated strain of HIV, then it could explain the "carriers" thing, a little known fact is that there are certain people immune to HIV, who, once they contract it, carry it around in their body for the rest of their life and can infect others with it, but their cells lack the receptors that allow HIV to take over a cell.

The infection is a mutated strain of the rabies virus as far as I know, and some people are immune to it (for now, at least). The '3 men, 1 girl'; thin is simple coincidence. Fadm tyler 14:32, March 19, 2010 (UTC)

Screenshots Edit

Does anyone have any high quality screens of the CEDA maps in Crash Course or The Hotel? They would make fine additions to this article to show the spread of the infection.--Jiangyingzi 13:14, November 20, 2009 (UTC)

Green Flu?Edit

Who renamed the article green flu? I say we change it back to just The Infection--Djj51 06:38, November 21, 2009 (UTC)

There are three official sources that support "Green Flu", so I think it's safe.
Yeah ok can you post some links and sign your posts to--Djj51 15:08, November 21, 2009 (UTC)
Green Flu is alright. Aratinga A.Ѭ 15:33, November 21, 2009 (UTC)
I just changed it back to The Infection. We've known it as the Infection for more than a year, so we shouldn't change it to Green Flu with so little info on it being called that.--'Meester SHOGUN450 ROAR! 18:44, November 21, 2009 (UTC)
can't argue with offical sources, but still, links or it didn't happen--SS4FireFox 18:59, November 21, 2009 (UTC)
Why would we call it the green flu? A newspaper article that says green flu is bigger the "Two weeks after first infection"? Or how 'bout the fact that it's not even really a flu? Imperialscouts 19:23, November 21, 2009 (UTC)
In fact, I think the name should be changed back to The Infection, I mean... just because some newspaper cut out calls it Green Flu is not enough of a reason to change the Article's name to it. DeathBlade182 19:55, November 21, 2009 (UTC)
The enemies are called the Infected. A newspaper article most likely left before the infection hit calls it the green flu. WHY are we calling this page green flu? Three sources call it the green flu? How many official sources call it the infection? Imperialscouts 21:04, November 21, 2009 (UTC)
ya but someone just changed it back. Why cant we just agree that it is called The Infection. The virus has nothing to do with influenza.-- 22:18, November 21, 2009 (UTC)
It's not a flu. It was called the Green Flu -before- people started, you know, turning into boomers and spitters. It's the Infection. Just as many wall scribblings denote 'not a flu' to contest it anyways. My votes to change it back, if it matters. If anything, Green Flu should redirect to The Infection, not the other way around. DShadow 22:19, November 21, 2009 (UTC)

dam i don't like the Collon spacing, it makes everything go off to the side, but seriosly, one source is the newspaper, one source is the Midnight Riders' website,whats the third one?--SS4FireFox 01:48, November 22, 2009 (UTC)

Hey! Someone who actually thinks this page should be called green flu! Speak up! I feel like we're talking to a brick wall. Imperialscouts 04:44, November 22, 2009 (UTC)

I think the majority wants it to be changed back to The Infection, besides, think of all the articles which make use of the name, we'd have to change them all... also, Green Flu sounds like a joke. DeathBlade182 06:51, November 22, 2009 (UTC)

Third one's Ellis' youtube page.

I believe we should use "Green Flu" as it's the official name VALVe have given to it, but "The Infection" works to as it's what the game gives it. Both work, really. StrongIntelligent

I don't think it's the official name. I think it's the name given to the infection in the Left 4 Dead universe before anyone really knew what it was. Imperialscouts 23:28, November 22, 2009 (UTC)

Green flu is just the commoner's term for it, just like how swine flu is the common term for H1N1. Until I see valve use it officially(Midnight riders and ellis's youtube channel dont count for me), I will not support it .--Djj51 20:49, November 23, 2009 (UTC)

EXACTLY! Especially because (uncertain on Ellis's) those came out before the infection was really known. Now we need an admin. YO! SOMEONE CHANGE IT BACK! Imperialscouts 23:00, November 23, 2009 (UTC)
Sorry, for some reason they are insisting that its called Green Flu. I agree with you though; until Valve starts calling it that, it should be The Infection. But Five Dog protected it so it couldn't be moved again, so there's nothing we can do. Maybe when Valve never calls it the Green Flu, the admins will come to their senses and change it to its correct name.--'Meester SHOGUN450 ROAR! 03:10, November 24, 2009 (UTC)

Hey everyone, chill out! Do not turn the Wiki into the Steam Forums where all you do is complain about the administration. We might not make everyone happy, but we do our job. This wasn't made to make everyone rage and start complaining. We discussed this topic thoroughly and we ALL came with the conclusion that it should use the name given in the newspaper. It's not like we came up with it randomly, it was actually in the game. What more proof do we need than that? Do we believe this is the real name for the disease? No. We know it's cosmetic. It's like calling acute viral rhinopharyngitis "The Common Cold". But we'd rather have the name disclosed to the public than just calling it "The Infection". If a scientific diagnostic is released, we'll change the name to that. But we're not changing it back to "The Infection". If this angers you, then I'm sorry. But I just want you to realize that you are arguing over the name of something on a game, over the internet, when you could be doing something much more constructive. So yeah. Green Flu. Take it or leave it. With love, Jo the Marten(Shriek) ಠ_ಠ 03:40, November 24, 2009 (UTC)

Yeah, you gotta point. You sure we can't, ya know, vote on it or something? And I never (intended) to attack admins. I think you guys are doing a great job. Half of it was meant as humor, but that's harder to show over the internet, isn't it? Well, sorry for any insults, intentional or not. Imperialscouts 05:33, November 24, 2009 (UTC)
Well, it's not like I want to sound aggressive or anything, but who exactly discussed the topic? Because you know, if you ALL came with the conclusion Green Flu was appropriate, then why are so many of us complaining about it? But of course, I could have just missed the discussion entirely... So yeah, I think there should be a voting or something. DeathBlade182 06:00, November 24, 2009 (UTC)
Five Dog, Stigma-231 and I discussed it in the IRC. A few other members were there as well like I'm sure Crowbar was, and the decision was pretty unanimous. I don't see why this is even being argued still. It's called Green Flu in the game. Jo the Marten(Shriek) ಠ_ಠ 06:53, November 24, 2009 (UTC) There's your link. A site made by valve, even says "The Green Flu don't stop the F'n riders.--L4DEX----- 05:42, November 24, 2009 (UTC)Left4DeadEX

Right, but isn't that supposed to have been made before the infection/green flu/whatever took over? My only problem with this is that we're using a cover up name that is most likely not it's real name. Sure, we may not know what it's real name is but we do know the survivors call it the infection (a lot). That's in game too. Imperialscouts 14:19, November 24, 2009 (UTC)
Whao whao, wait, what? I don't remember them ever calling it the Infection...if they did that was only because they didn't know what it was, as it hadn't received a yet. Jo the Marten(Shriek) ಠ_ಠ 14:37, November 24, 2009 (UTC)

What if we changed it to The Infection and made a mention of it being called "Green Flu"? Maybe saying that some sources called it "Green Flu" and that that was probably what it was known as before people knew about its effects. Diachronos 14:42, November 27, 2009 (UTC)

The page titled 'The Infection' and a note in the Trivia section about the 'Green Flu'? I'd agree with that one. Fadm tyler 20:57, November 27, 2009 (UTC)
Yeah, what's wrong with that? C'mon, don't we get a voice too? Imperialscouts 04:21, November 29, 2009 (UTC)

I have proof in quotes that the survivors call it Green Flu

  1. Coach: [reading notice]"Report the sick..."
  2. Ellis: "Report the sick?"
  3. Rochelle: "Don't worry Ellis, they mean the flu, not in the head."

See, The flu --SS4FireFox 06:51, November 29, 2009 (UTC)

If we are to call this article green flu why shouldn't we call the page the infected to the green flued that is what this page sounds like to me a n00b way to call the Infection by a name.


i miss the internet
No shit,shelock , would you call someone who has the flu flued? no, youd say they have the flu, and we can't be calling articles that, Its an infection, the ones infected by it are infected with it, but Green Flu is the officail term for it.--SS4FireFox 04:30, December 7, 2009 (UTC)
"Well, at least I didn't catch the flu."

Jo the Marten(Shriek) ಠ_ಠ 05:37, December 7, 2009 (UTC)

What makes this whole thread ironically amusing is that thanks to the HAZMAT suits in L4D2, I'm beginning to question whether or not the "Green Flu" is even an "Infection." If it's not transmitted by bodily fluids and its not airborne, what causes it? Not EVERY single dude in a HAZMAT suit ate contaminated burgers at the Burger Tank before dressing up. Perhaps the argument shouldn't be about whether it's Green Flu or Infection, but whether or not either of those names are suitable. What do we call it after Valve confirms they've sent us on a wild goose chase and it's nothing like rabies at all? LOL! ZachsMind 03:52, December 8, 2009 (UTC)

I don't care anymore. I can understand both sides of the arguement. Let's go focus on something more important. Imperialscouts 22:04, December 22, 2009 (UTC)
uh, my fortune cookies says "every words coming out of your mouth shall spread through every one you know." but why it's written by pencil and looks like a third grade kid's writting?, by the way the HAZMAT seems to be lacked the seal on their hands and legs, i mean the suits looks like only a long-sleeve suit with face cover, and overalls.Crazy al594 13:14, August 22, 2010 (UTC)

vandalism Edit

Yeah, someone deleted the whole thing.-- 19:33, November 21, 2009 (UTC)

Actually, we just had an administrator collision. The page was moved by two admins at the same time and effectively, the original page cannot be found. We're currently working to resolve the problem. Please stand by, and don't edit the page unless you have the original one off by heart. Which I doubt. ;) --Five Dog TalkRead 19:38, November 21, 2009 (UTC)
There we go. Crisis resolved. Have a pleasant day. :) --Five Dog TalkRead 19:54, November 21, 2009 (UTC)

"First Infected" Edit

It makes no sense for the body in No Mercy's hosiptal to be the original victim of the disease, because if the disease had started in Mercy Hospital, it wouldn't have been a viable extraction point as discussed in the grafitti in every safe room leading up to that point. The infection had to arrive after the hospital was being used for extraction, which of course would have to be after the infection became so widespread in the first place. Just sayin'. Grabbinpeels 17:55, November 22, 2009 (UTC)

And the "missing thumb infected" cant be the original as it had gotten its thumb bitten off.--Atlas Lied! 14:22, November 26, 2009 (UTC)

Original Outbreak Edit

At the beginning of Dead Center, in one of the first rooms, there appears to be the remnants of a CEDA briefing on the Green Flu. Amongst other things, there's a map on the table showing the places currently infected (pretty much the entire eastern USA) and dark rings showing the epicentre of the outbreak, which appears to be Pennsylvania (but then Im British and have no clue about what state is where). Could somebody screenshot and write up about that?

I added the picture and wrote something just to get it on the page; I'm sure other people will want to edit it further. -Grabbinpeels 17:55, November 22, 2009 (UTC)

I actually have to disagree with this. While Pennsylvania would make sense thematically (most of George A. Romero's Living Dead movies have been set in or around Pittsburgh, PA), the infection chart image displays three shaded rings emanating out from a red circle that is, presumably, the origin or epicenter of the infection. This point does NOT appear to be in Pennsylvania; it's too far east. It seems most likely, in fact, that it's centered on New York City, which would make sense from a practical standpoint. New York is one of the most heavily populated cities around, and would be a prime target for a deliberate biological attack, for the same reason a completely accidental outbreak would be problematic; so many people in such a small area means the infection will spread rapidly. As such, it could even be that the map is not indicative of the origin of the infection, but rather the levels of infection present (areas closer to the center might be completely overrun, while areas further out might not have quite as many zombies), and that the infection itself may have still originated in Pennsylvania, but quickly spread to New York. (It's also possible this might have been a mistake on Valve's part, though; anyone from Pennsylvania, and Harrisburg in particular, knows Harrisburg should not be that clearly visible on a map of the whole country, while Philadelphia and Pittsburgh should be visible [yet are not on this map].) --Dan Dark 23:17, January 4, 2010 (UTC)

I see someone modified the main page to state the infection started in Philadelphia. And, upon closer examination of the image, and comparison to a normal US map, I feel inclined to agree. I hadn't previously realized Philadelphia was quite so far east, and although it's hard to make out whether or not Philadelphia is labeled, the point immediately above what I can only assume is Philadelphia is definitely Trenton, which is accurate. It's still difficult to tell exactly, and a higher resolution image might help (any of the PC players feel like digging through the .gcf files for it?), but Philadelphia is definitely close, at least, and more accurate than simply saying "Pennsylvania." Dan Dark 01:52, January 9, 2010 (UTC)

Note on Virgil's Wife Edit

Virgil specifically says that his wife was bitten. In one of his possible dialog responses to the Survivors calling his boat on the radio, he says that he's glad to hear from them as it had been quiet since his woman "got bit," and presumably was infected. I don't recall any mention of Virgil infecting her with a kiss as is stated by the article, but then again, there are numerous potential dialog responses available. Atypicaloracle 04:47, November 24, 2009 (UTC)

Vandalism... Edit

Crazy sons'of'bitches messin mah article up! I can't undone the vandalism due to the multiple vandalism done in this page. Any admins in the house? Aratinga A.Ѭ 21:53, November 27, 2009 (UTC)

lol, I forgot about that special button. Nevermind my comment above :D Aratinga A.Ѭ 21:54, November 27, 2009 (UTC)
Just use the history button, then selected revisions. StrongIntelligent
I know, I forgot I could do that ^^ Aratinga A.Ѭ 21:59, November 27, 2009 (UTC)

Block of the page Edit

Why we don't block the page due the recent vandalism is happening there? Aratinga A.Ѭ 14:22, November 29, 2009 (UTC)

Interesting FindEdit

I was glancing around the game, and I noticed something that could tell us a bit more on the special infected. Specifically, CEDA's pie chart.


The color codes are in the following order: Common, Charger, Spitter, Tank, Boomer, and the rest are covered. As we can see, special infected do not mutate from Common infected who live for a long time. And, now we know that the Boomer probably ranks as one of the most common special infected around, only beaten by whoever is the dull yellow piece of the chart.

And by that blue-green wedge. I also noticed that there are only 7 sections apart from the Commons. My guess would be that yellow is Hunters, teal(?) is Smokers, and purple is either Jockeys or Witches. Diachronos 23:39, November 29, 2009 (UTC)

I zoomed it in and from what i can tell the colours mean from the refrence thing(it's a little blurry, also i can't rember whats the refrence thing is called at the current time) Common-red, Hunters-orange, Tanks-Pink, Chargers-green, Boomers-brown, The other names are covered by the memo so i can't tell - Fireside 30/11/09

Symptoms Edit

I know this is on another chat page, but... Now that it has been buried, I might as well put it here. Ok, now that we have seen regular infected, we don't know who they were before becoming infected, so now through the Jimmy Gibs Jr model and the humongous banners showing what he originally looked like allows us to take a closer look into the infection. Here are symptoms I have came up with:

(Universally among infected): High fever, vomiting, headaches, Extreme aggression and irritibility, adrenelin is put in overdrive when a person or object is viewed as not infected, trauma/loss of sanity, various internal recombobulations or whatever the words are, various spasms (During transformation), pale skin, loss of appetite, increased lung capacity, bloodlust, loss of self preservation, gagging, hypersensitivity, and coughing. Oh, and a tendency to burn as if covered in oil even when totally dry.

Now for special infected starting with everyones favorite barf bag!

Boomer: Cysts, constipation, burping, projectile vomiting, extreme weight gain, explosive diarehha (when killed), and rips in skin. I do believe the stomach becomes the source of bile, in a form of modified stomach acid, and as a puss filled bump does not pulsate, the cysts have additional bile in them.

Hunter: Loss of eyes, increased muscle mass, alot more lung capacity, hypersensitivty focused towards hearing, growth of claws, screaming for no visible reason, and a tendency to crawl. I can believe that a regular infecteds strength comes from adrenelin, not increased muscle growth, but no man, unless he had adrenelin instead of blood, could jump over a 2 or 3 storie building without atleast increased muscle mass towards the legs.

Smoker: dry cough, excreting unknown gases from who knows where (not the buttox cuz the intestines have disconnected), vomiting out intestines, puss filled lumps, spine elongation, appears to deflate when skin ruptures deep enough, and increased muscles in abdominal region (How else can they pull a survivor so far?). I believe the intestines of fused with the tongue which causes increased stability, yet I still have no explanation for the smoke around them.

Witch: Extreme depression, hatred of many things especially sudden light and loud noises, finger elongation and hardening of additional ligaments in the fingers, increased nail growth, EXTREME bloodlust to anything that startles it, and whitening of the hair. I dunno what causes the witch to go in such a rage, but I figure the crying is the depression.

Tank: Extreme upper body muscle growth, rage at the sight of anything thats not infected, heart tends to explode from a combination of stress, frustration, and adrenelin rush, strengthening of fingers, and performs better when on fire.

Yes I just copy and pasted most of the stuff from it but I say it goes better here. --Prof. 02:02, December 8, 2009 (UTC)

One thing that I noticed you missed was that normal infected tend to have bleeding eyes. When you see the dead normal people in the Parish, you'll see that none of them have bleeding eyes. Oh, and with the Witch, I saw this one possibility for her crying; Her pain receptors weren't entirely turned off, or are still completely active. Thus, the mutations hurt her to such a great amount that she cries and usually sits around in pain. When it's day time, the Witch could be trying to find some darkness to hid in because of her hypersensitivity causes her to hate the sunlight.

Cool man. All we need now is the medical terms for all those symptoms. If it wasn't fan based we sould make an article about it! DisMEMBAH 19:49, April 27, 2010 (UTC)

I agree with the DisMEMBAH above. Thats all fine and great, but we would need some form of name for the invidual medical state of the Boomer, Charger, Smoker, and so on. I really does no good to tell us something we can go into the game, and take a 3 second glacnce to figgure out. However, there is something that really bothers me about something you said in your discription of the Tank: "Preforms better when on fire" I'm sorry man, but when I read thoes five words, thats when I lost all credibility for you. All of the other symtoms you listed for every special infected were possible in the real world, (with the exception of a handful, but, its a video game, so anything is possible) but seriously, "Preforms better when on fire"?! What the heck is that? Don't get me wrong, I am NOT discredting this entre post because of that, but it just kind of made me think, "Wow. Maybe I can get bit by some random drug-nut, grow arms the size of tree trunks, lite myself on fire, and go kill everyone in the world!" And besides, everyone has been in this situation: Your playing Left 4 Dead, you have been on a hot streek since the very bigging of the round, its the fanally, you get to be the tank with only Bill left alive. You coming straight for Bill, about to get him when he throws a Cocktail at you, and you catch on fire. Now, at this time, you have two options: 1) Jump off the building like a noob; or 2) Try your darndest to get Bill. I think you would go with option number two. So, there you are, chasing after Bill, on fire, as the hellicopter is coming to pick Bill up. Your one foot away from Bill WHEN... You run out of heath because of the freaking Cocktail! Then what do you do?! Because of you, your team lost by 10 points! You can eather: A) Leave the server, never to return; or B) Get kicked out of the server by pissed off people. Eather way, it was becasue of someone reading this post, and going, "Getting lit on fire while playing as a Tank can only be good for me in a versus match!" I'm not taying to sound pissy about this, but it just kinda made me go, "Wow. Just, wow." Thanks for letting me rant. 20:47, May 22, 2011 (UTC)sodaman667

Becoming Infected Edit

If the zombie virus is a mutation of the rabies virus then someone doesn't necessarily need to be bitten in order to become infected. Contact with ANY bodily fluid (blood, sweat, tears, boomer bile, etc. etc.) can infect someone. The zombies in Hazmat suits were more than likely bitten through the suit. Also, contact with a contaminated surface (door knob, gun, frying pan, whatever) can cause infection. Even immune survivors can carry the virus in their bodies and pass it on to others.

The following is a section from the Rabies article on Wikipedia:

Rabies is a viral neuroinvasive disease that causes acute encephalitis (inflammation of the brain) in warm-blooded animals. It is zoonotic (i.e., transmitted by animals), most commonly by a bite from an infected animal but occasionally by other forms of contact. Rabies is almost invariably fatal if post-exposure prophylaxis is not administered prior to the onset of severe symptoms. It is a significant killer of livestock in some countries.

The rabies virus travels to the brain by following the peripheral nerves. The incubation period of the disease depends on how far the virus must travel to reach the central nervous system, usually taking a few months. Once the infection reaches the central nervous system and symptoms begin to show, the infection is practically untreatable and usually fatal within days.

Early-stage symptoms of rabies are malaise, headache and fever, later progressing to more serious ones, including acute pain, violent movements, uncontrolled excitement, depression and inability to swallow water. Finally, the patient may experience periods of mania and lethargy, followed by coma. The primary cause of death is usually respiratory insufficiency. 97% of human rabies cases come from dog bites. In the United States, however, animal control and vaccination programs have effectively eliminated domestic dogs as reservoirs of rabies.

getting bitten through the suit is not possible, if you shoot a limb off a hazmat infected,you can hear the noise of wind escaping their suit--SS4FireFox 05:33, December 13, 2009 (UTC)
Church guy was human for at least an hour before turning. plenty of time to bandage the wound, throw on the hazmat suit, and go to work for the worlds worst emergency managment agency--AstralShapeShifter 10:15, December 13, 2009 (UTC)
and lets not forget the other times listed on the saferoom walls,from 5 minutes to 3 days.--SS4FireFox 19:43, December 13, 2009 (UTC)
Like it said in the article, infectious material can survive on surfaces. Usually the HazMat division would have to decontaminate themselves before and after wearing the suit. Human error is always present, so perhaps the few HazMats that turned into UCI didn't completely decontaminate themselves. This is evident since they are handling Boomer Bile, fluid from one of the more potent infected. Plus, during the initial outbreak (which, since it's only 3 weeks in by L4D2) they probably didn't know how serious a bite or claw wound would be. Would have been damn horrible for them to find out after being bitten that they would turn into zombies with no hope of a cure. Deathhacker 22:15, January 16, 2010 (UTC)

Going with the Wikipedia article, that sounds a hell of a lot like The Infection form Left 4 Dead. All those symptoms match. Well, at least in the case of the common infected.DisMEMBAH 19:52, April 27, 2010 (UTC)

Hunter Bite... Edit

The image at the bottom looks more like someone dropped a ragdoll and top of ellis. Can anyone confirm wether or not it's real? -- 22:13, December 22, 2009 (UTC)

The hunter can bite if it has someone pinned DisMEMBAH 19:52, April 27, 2010 (UTC)

Rochelle's intro quote Edit

What does Rochelle say during the intro, when the Spitter appears; grim or gross? The subtitles apparently say 'grim', but the video doesn't seem to have the 'im' sound in the word anywhere... I'll just ask here to avoid a possible 2-editor war starting, though I've known many subtitles to say the wrong thing before. Fadm tyler 18:09, December 26, 2009 (UTC)

I'd be fine changing it back to "gross," once we get a general consensus/admin approval. I think it sounds more like "gross" but I'd like to be sure the subtitles are wrong before we change it. (and thanks for being civil) The Deep 1 18:20, December 26, 2009 (UTC)

Wow Edit

Just read this entire page and I was almost consirned that the infection was real. That's when I realized that I'm still alive. Anyway, say the infection was real. Do you real think someone who was immune would have the balls to kill a bunch of zombies in an attempt to survive? Well, they would actually, but if I were immune I'd much rather barricade my house, stock up with guns and snipe zombies from my bedroom. Or even better, I'd work to make it so I could mutate into a Tank and still have sanity. That'd be awesome, except my jaw would be fused into my neck and I couldn't talk.

Humans are capable of great evil when they need it, some probably wouldn't need a reason to kill. If you kept your sanity (assuming that was possible), being a tank would be even worse because the muscles seem to be too big for the skin to cover, at least the proper tank is too dumb to feel it. Fadm tyler 14:28, March 19, 2010 (UTC)

Along with the pevious statement, humans are capable of great feats of survival when the situation calls for it. If it's a matter of survival, we will do whatever it takes. Nuff said. DisMEMBAH 19:55, April 27, 2010 (UTC)

Symptoms Edit

We have a bit in the notes about it, and we can tell from the helicopter pilot and Church Guy, I think we could make a Symptoms section. Who's with me? Jo the MartenMini Hunter(Shriek) ಠ_ಠ 19:19, January 26, 2010 (UTC)

Yeah, why not? Although the only symptoms I can think of are feeling cold and some coughing, maybe paranoia in the Church Guy's case, but that didn't happen to the helicopter pilot. DeathBlade182 07:05, January 27, 2010 (UTC)
I was thinking like chills, coughing, vomiting, animalistic rage, loss of pigment, strengthened muscles, more endurance, etc. Jo the MartenMini Hunter(Shriek) ಠ_ಠ 07:12, January 27, 2010 (UTC)
Don't forget potential insanity a la Church Guy. ZD, 17:40, October 7, 2010 (UTC)

What is it?Edit

What is this? is it a bacterial, viral, or perhaps even a fungal disease? Post thoughts below. --Djj51 03:25, February 3, 2010 (UTC)

Parasite. Read this. --Ichverbot 04:31, February 3, 2010 (UTC)

Isn't it possible for the virus to be airborne? Just because one piece of graffiti says it isn't doesn't nessecarily mean that's true. Or maybe it mutated or something... LazyLord777 02:28, March 21, 2010 (UTC)

There's no evidence taht I know of that says The Infection didn't go airborne, as is certainly implied by the PPE's that CEDA used. Most viruses do tend to go airborne in time. DisMEMBAH 19:57, April 27, 2010 (UTC)

Have you ever noticed?...Edit

That the survivors, not the mention the infected, all have black, brown, and/ or dark colored hair? Where are all the red heads and blondes? Other than a few gray/ white haired infected (Witch included), there isn't that much evidence of redheaded or blonde infected or non-infected. So... what's the big deal? Does the strain of virus just totally eliminate them? Does it cause their hair to change to black or gray?

The Infection changes your appearance, explaining thier lack of variety. There are several billion humans, but only 8 seen survivors, not much room for vaiety. Fadm tyler 14:22, March 19, 2010 (UTC)

Infection transmission Edit

I personally think it is spread by fluids (blood, saliva, ect.). Special infected also show enhanced forms of transmission. Smoker airborne spores. Boomer infected bile. But also from a defensive force. By killing treats to the virus. Posted by: Unknown

Special infected actually show lesser forms of transmission (if at all). The charger, jockey, tank, and witch have very few instances where proper transmission could occur. This is because there is little to no interactions outside of actual physical contact between these four special infected and survivors. Therefore, I'm extremely skeptical at the chances of a tank being able to pass on the virus when the only contact between a tank and I is when it throws a rock at me. Other special infected may have success but your ideas are flawed. A smoker would likely transmit the disease via his saliva-drenched tounge, not because he produces a green smoke (which does not contain spores, because there is no such thing as a viral spore). Boomer infected bile could transmit the disease, but then why would it also act as an attraction for other infected? Not only attract but induce attacks against the bile covered victim? Assuming it is bile, then because of bile's high acidity, the virus would likely break-down as a result and not be viable for transmission. However, since the bile in this case does not cause damage to the survivors, one can assume that boomer bile is actually more neutral than acidic. If this is the case then yes, the bile could contain the virus. However, the same cannot be said about the spitter who does expel a highly acidic substance and causes damage to survivors. In her case, there is no way that the "spit" could transmit the virus. So then, how else could a spitter transmit the virus? The hunter bites, that's an applicable route of transmission. So for definite forms of infection transmission (assuming non-airborne pathogen): Hunter-biting, blood ingestion; Tank-blood ingestion only; Smoker-contact with saliva on tounge, blood ingestion; Boomer-blood ingestion, maybe bile/puke ingestion; Witch-blood ingestion only; Spitter-blood ingestion only; Jockey-blood ingestion only; Charger-blood ingestion only.Shawty71 17:16, July 14, 2010 (UTC)

Vampires.. Edit

In The Passing, Francis asked the Survivors if any of them were Vampires. It seems odd for him to ask that to clearly non-infected people when in Left 4 Dead he thought all zombies were vampires. Later in The Passing, a dead body was found with a single bite mark on his neck. Could the carriers have vampire-like qualities? Could they still mantain their humanity to be mistaken as survivors? Could Valve be hinting that the carriers/vampires are yet undiscovered Special Infected?
Whoever added this clearly doesn't get the running joke. Unless anyone has any objections, it should just be removed.Goose511th 20:25, May 12, 2010 (UTC)

Its just a running joke on Francis's and Ellis's behalf. It's not meant to be taken seriously like you did. sign your posts as well. Chubbyhug 22:37, May 12, 2010 (UTC)

Lets not compleatly discredit the whole "Vampire Quilitys" idea from the tabe yet. I understand that this person may or may not have played Left 4 Dead 1. Having said that, if you have played Left 4 Dead 1, and you STILL don't get the running joke about Vampires, then you really need to evaluate what your doing while playing this game (Masterbation maybe? Not to sound crude, just a joke.), and/or realise that your a big fat failure. Now then, back to my origonal idea about not discrediting the Vampire qualitys idea. How many zombie movies or T.V. shows have you seen were the zombie does not go for the neck first? For me, one (The Walking Dead, Season 1, Episode 4 were Amy is bitten on the arm, adn then the neck). And that is out of about 50 or 60 zombie related movies, T.V. show, ect. And this same premise goes for Vampire movies. I have never seen Vampire movie that the Vampire has not gone for the neck first. Not saying Goose511th and Chubbyhug's idea is wrong or not a good idea, this is just what I'm saying.

Thanks for letting me rant. 21:07, May 22, 2011 (UTC)sodaman667

The disease coming from cows Edit

I find it much more likely that this is another reference to Dead Rising, where the zombie disease was created to provide endless livestock or something similar... it's been a while since I played that game. --Xaerun 03:19, May 16, 2010 (UTC)

CEDA infected among other things Edit

Part of the article brings up how the CEDA infected are wearing suits designed for airborune viruses, and how they don't appear to be bitten, as their suits have not been previously peirced. It provides an explanation, that they were bitten before they put on their suits, but I have another idea. What if the Green Flu started out non- uh... Zombieish. with victims simply showing flu like symptoms before dying, This lead to the name Green flu. The virus was also airbourne (like the flu) allowing the CEDA zombies to be infected without being bitten. Then, Spontaneously the Infected became violent and all assumptions it was a flu were discounted.This transformation overwhelmed CEDA and the government handed control of the newly war-like situation to the better prepared United States Millitary. 04:22, May 16, 2010 (UTC)

This Game Edit

Seems to be about killing zombies. Wouldn't it be funny if Valve didn't care how plausible it is that one viral strain can create several different mutations of Infected? What if, and I'm speaking hypothetically here, the purpose of different types of SI was to add variety to the game?? I mean it's crazy that game designers would make a hissing noise come out of CEDA suits just to spur on the wild speculation on Green Flu's mode of transmission! And where does the name Green Flu come from anyway? My theory is that they named it after the box cover. I propose deeper scientific examination of this "game" to understand better the effects of a zombie outbreak.

This has been said before, its just a name, like swine flu. And the game has been examine, not scientificly, theres nothing scientific about a game where you kill zombies and mutated shit. Pretty much everything has been uncovered, through gameplay or looking at the games files. possibly named aftwer the first games box cover, but thats just a suggestion, not fact. and unfortunately, we dont know exactly how it spreads. LOLKING 17:53, May 18, 2010 (UTC)

It's still fun to speculate. Nightmirage 18:10, May 18, 2010 (UTC)

Maps Edit

There where a few older CEDA maps from l4d1 that showed other areas the infected hit we should definately find those images and put them back up. Im not having any luck in finding them.

--Gwax 19:26, May 23, 2010 (UTC)

Virology Edit

I have a theory on how so many strains of the infection popped up in so little time.

I think that the Green Flu virus is very sensitive. All viruses reproduce by messing

around with a cells internal workings, and if the Green Flu virus is sensitive enough and

infects a messed up cell, the resulting viruses would likely be messed up to and

therefore a new strain capable of causing new symptoms. If the virus changed inside

a host, any people the host infects would have the new strain.Sciencematt123 22:13, October 6, 2010 (UTC)

This DOES makes some sense as to the existence of Special Infected and the spreading of the Outbreak achievement (scroll down a little to see the achievement). I just love how the Green Flu hasn't mutated to create easy-to-kill Infected besides Commons. :\ ZD, 17:34, October 7, 2010 (UTC)

I presume that any sort of strain that created a weaker type of Infected than the Common died off. 19:22, October 19, 2010 (UTC)
Natural Selection: sucky zombies get shot75.7.193.80 21:26, October 20, 2010 (UTC)

Process of Infection Edit

This could most likely have been added on to other topics, but I'll do it anyway.

What ARE the symptoms of the Green Flu? I belive Valve has left it to us to figure it out, and I think I'm close to the answer.

Here are the symptoms of the Infection in a healthy adult:

Hour 1: Pain in bitten/scratched area; pain in chest from inhalation

Hour 2: Person ignores the pain, takes antibiotics (from CEDA!); slight dizziness

Hour 4: Body starts to fall to the Infection, person in more pain; increased dizziness; person goes to CEDA evac to escape other turned idividuals.

Hour 8: Coughing, lightheadness, pain all over, slight dementia; CEDA lets person into population with Infection

Hour 12: Primial instincts set in; loss of capable vison, high fever (100-104 degrees farenheight)

Hour 24: Subject rendered insane in the brain; CEDA brings tainted idividual(s) to a hospital (like Mercy Hospital)

Day 2: Infection takes over weak individual, turning into common infected

Day 8: Infected structure weakens to abnormal levels

Day 14: Individual mutates to Special Infected; due to mutate completely in less than 4 hours

This varies from person to person, and can occur in days or in less than an hour (in Church Guy's case.)

What do you guys think about this?

Nerf Veteran 10 15:34, January 2, 2011 (UTC)

correct me if im wrong, but i dont think you have enough proves for this.

according to Grafitti time it takes to turn variates but can happen in 5mins, like the soldier boomer from the comic, the church guy uses cirka an hour.

no children or animals are seen infected in the game, the only thing i can take from that would be that the green flu is too "powerfull" for them, meaning they die from it instead of turning infected.

there is nothing that states the infected are "reanimated" they are simply mad with their infection.

Hengara 16:18, January 2, 2011 (UTC)

Thank you for pointing this out. I was going a little bit non-canon, but i'll edit the top to fit your description.

I also belive that the Infection is deemed too "powerful" for their systems, thus killing them before they can go insane and become totally Infected. The same also goes for animals, or at least most of them, because you can hear a dog barking in the Zombie Survival Guide trailer for Left 4 Dead 2 towards the beginning.

Also, going on the variation, i tried to include the variation of the time it takes to turn, but i didn't make it obiovus. sorry :( . I also think that the immune system affects the time until one turns into a common infected, like the Church Guy or Soldja Boomer.

Keep the posts coming!

Nerf Veteran 10 00:15, January 3, 2011 (UTC)

about the dog in the Zombie survival guide, i noticed the dog too, i don't know if that's just a normal dog or an infected dog, but i think it should be noted that in the soudfiles for L4D1 you might find a folder called "infected dog" some of these sounds are actually used for the hunter (thats what i've heard). + in the church in Death toll, there is a newspaper stating that several dogs in the area have gone missing. i dunno about you but to me it seems VALVe was going to ad an infected dog but for some reason didn't

well of course the immune system effetcs the time it takes, seems to be VERY varied tho, so there is probably more too it than just that.
Church guy was bitten one hour before.
According to the chopper pilots cut lines, (might not be canon) he was "hit" just before he speaks to them through the speakers on the helicopter. i dont know how long that might have been but probably over an hour.
The pilot from Dead Air, did (acording to comic) also turn, but as far as i know, he hadn't been bitten so i suposse he was infected through the survvivors breath or something similar, but i wouldnt know how long it took for him to turn.
Lt.Mora in the comic, cant have taken long, but then again, he had probably not turned completely even tho he'd been bitten, scratched, and maybe even bleed on.
Carolyn from comic takes a few minuttes only after being bitten. thats all the only valid examples i could think of.
Hengara 14:53, January 3, 2011 (UTC)

I saw your comment about the sound file, and apparently Valve was reusing it for the hunter, and I played the game, and i also found the newspaper in death toll. I don't know why Valve cut the zombie dog, but im glad they did. It seems a little more realistic that way. And adding on to the variation besides the immune system, i think that maybe the more the infected individual was exposed to the Flu, the quicker they turned (example: Mora gets bitten or scratched, then he gets bled on, scratched even more, then is on the verge of turning.)

Nerf Veteran 10 00:49, January 4, 2011 (UTC)

yes it might seem more realistic, since this is mainly the reason i beleive the green flu is (as i already said) too powerfull. but i also think it would be great to see something other than humans being infected, maybe something like cows or bulls in blood harvest, or something similar.

yes, yes of course it has something to do with how much they are exposed, Mora must have been bitten a bunch of times so i'd say his immune system wasbe really great. as for the scratches, i dont really know if the infection can be transmitted that way. but as you probably know, the infection is supposed to resemble or be a mutated version of the rabbies virus, and i'm pretty sure rabbies is bloodborne.
of course when it comes to people who are immune, some of them might be immune only to breath, and not bite, do you know of any indications of this?

Hengara 17:14, January 5, 2011 (UTC)


I understand, it's not P.C to have zombie children. (Although, the new game "Dead Island" seems to have missed that memo...) But it seems VALVe intended children ( Zombies or corpses) to be in L4D and L4D2. In Blood Harvest, there is a child's room and a crib. In Hard Rain, there's a playground and a treehouse. in Swamp Fever there are many teddy bears in the plantation house. There are more I'm not quite remembering, Can anyone back this up more? 04:04, February 26, 2011 (UTC) :)

Yeah I thank story wis there are Infected kids (and maybe some animals) as well as corpses but are not seen in game for being to crule (kinda like how RE2 was going to have kid zombies) I dont see why some people thank it could be to powerfull for kids(but its a good theory) we know next to nothing about the green flu but what is given to use in game and thats about has much as the Survivors know with that said there is grafity on the walls saying things like "the kids are ok met us at (insert random place)"

Final Solution? Edit

As it was stated on the article, the infection may be climate-based. Annnd what happened to mexico? My guess is, that the mexico Govarnment and the UN quarantined north america, stopping anyone from going in or out.

It would be difficult to quarantine the country, considering there seems to be civilian evacuations not working with the Military. That a lot of people aren't inclined towards rational thinking means some are likely to try and get through anyway. That's also assuming the infection hasn't already left America Fadm tyler 13:27, September 9, 2011 (UTC)

how I think the infection started Edit

This is how I personally think how the infection started, it started out airborne but then went to focus on evolving the victems but of course It would need some sort of base to evolve on.So then the virus saw the special victems and started to mutate them!And then (I am going to call the virus V ) V realized to evolve it would need sugar so it sent the witches to scout for sugar. Then a witch found a sugar mill and that all ended a day or 2 before you control the survivors sorry if I missed any plotholes becuase this is just based of my knowledge of the game beceuase I never actually played the game.Also you can call me alfred2002

The base would be Common infected, to start, I don't see how Green flu was a organism with eyes in it, so it couldn't see differences, so that's kind of out, witches were a late mutation, and an article inside the page says that witches went there from malnourishment. No offense or anything, but do you in fact own the games? Also, not a forum. 19:34, January 25, 2012 (UTC)

Another mutation possibility... Edit

It's also possible that people mutated further based on previous shots, such as a flu shot, chickenpox shot, etc. These shots may slow the growth, or even halt the infection, therefore, the infected don't mutate into further forms due to these shots, as where the ones without these shots are more likely to, and almost always mutate further. Shadow-45 (talk) 17:16, November 6, 2012 (UTC)

Um I was watching Witch Hunter on Youtube, and the computer voice mentioned something about neurotoxins in regards to the green gas. 

There was one part of it that got me puzzled. The people in the building were gassed, but while most of them became infected, there was several guys in one area (the one you need to override the computer to get through, just beyond the safe room) who were still dead (and there was no gas).

Could that be something to note? 08:00, March 1, 2017 (UTC)

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