Swamp Fever

Swamp Fever is a new campaign spanning four chapters which takes place in a "swampy" location in Left 4 Dead 2 after evacuating from Savannah. The Survivors will reach this swamp and escape from it in a fishing boat familiar to the one in Death Toll. It was playable in Comic Con 2009 through July 23rd to July 26th. It seems as though it's a showcase for the AI Director's new, more in-depth level controls—such as the weather, and the new water system which slows the Survivors down and does not allow them to run.

Swamp Fever is the only campaign that will contain the Mud Men—Uncommon Infected that are hard to spot and extremely agile compared to the Common Infected.

Trivia

 * Swamp fever is a term given to a number of diseases that are acquired in wet, swampy environments.
 * Some of the walls in a shanty house found in Swamp Fever can be broken off with weapon damage.
 * Swamp Fever was the very first campaign to reveal the Spitter in gameplay videos.
 * In the video of this level you can see a paratrooper hanging from his chute. An OXM article says that they are randomly located on the level by means of the Director, and will signify item drops underneath.
 * Swamp Fever was the first campaign revealed to have 4 chapters (Dead Center was the second), as opposed to the usual 5. However, it is supposed to have the same duration as 5 levels, so it feels like a 5 level campaign.
 * All four chapters seem to have a Crescendo Event, with the exception of the finale.
 * The train the survivors start in some Swamp Fever videos has not been removed the same way police car was removed from Dark Carnival. Although it hasn't been removed, the survivors still occupy the train car and Ellis complains that Nick killed the Helicopter Pilot, in a similar manner to Crash Course. This brings up another thing, such as weapons and the helicopter crash itself. A theory could possibly be the survivors lost their guns while the pilot was becoming infected and they moved away from the remains of the helicopter to a safer place.
 * This campaign is set in dawn, from just before the sun rises to just after. The second half of the campaign is in daylight.
 * Just like the Helicopter Pilot in the Left 4 Dead, the Helicopter Pilot in Dark Carnival became a zombie. Afterwards, Nick killed him, bringing them in this campaign.
 * A Jukebox can be seen in Plank Country chapter.
 * In the first chapter in this campaign known as "Plank Country", a charger can be seen, dead, and hung up by his extremities possibly implying that he was tortured or used as a warning to outsiders of the dangers in the swamp.
 * The Stand-off Plantation finale features three Tanks. One after the first wave and two thereafter. A good tactic is to bile cover both and let them fight it out.
 * The PC version of Plank Country has a glitch in Versus mode that gives the survivors 500 points upon activation of the crank that calls over the river boat. The glitch also temporarily prevents the infected players from spawning.
 * The crashed Airliner in the the swamp could be related to Metro international Airport, as the destroyed airliners in Dead Air has the exactly same red color stripe.
 * In the area containing the river boat crescendo event, there is a Charger strung up on a signpost. It is in the shape and pose of the Lambda symbol, continuing Valve's tradition of sneaking the symbol into the Left 4 Dead titles.
 * The Campaign's tagline, "the only cure is dying", is a reference to the fact that there is currently no known cure for the infection. Or could be a reference to the survivors being immune, and presumably the only ones which a cure can be conjured from (although this seems unlikely as the saferoom graffiti in the parish indicates that while some people are immune they are still carriers of the infection and therefore are still affected by the infection so a true cure would be impossible to produce).