Infected

Infected, also known as Sickness as an April Fool's day joke, is a custom game mode in Call of Duty: Modern Warfare 3 which started as a private match game mode before being released to the online community public playlist on February 5, 2012 for PlayStation 3 and Xbox 360, and on May 9, 2012 for PC. It is also available in Call of Duty: Ghosts and Call of Duty: Advanced Warfare.

Call of Duty: Modern Warfare 3
The game starts with all players being survivors. In the upper left hand corner of the screen, there is a timer that starts with nine seconds counting down to the Infected. After the nine seconds, one player is randomly chosen to be first infected. The survivors are the players who are not infected, hence the name "Survivors". The surviving players must hide from and kill the Infected to try and survive until time runs out; each game lasts five minutes. The Survivors spawn with an unknown weapon (depending on what the custom settings are) and must survive by killing the Infected or hiding. 50 points are given to Survivors every time a Survivor is Infected. The name given with the points is "Survivor". The round ends when either the last Survivor is killed/infected, or time runs out, and the new round will start pending on a new player to be infected.

However, there is a twist in public Infected. Any place where the players will be notoriously difficult to knife by normal circumstances is a 'death zone', wherein a player (including the Infected themselves) will automatically die and join the Infected (if not already). This originally also applied to Private Matches, but community outrage led to this being reversed in Private Matches. Notable are listed below in "Death Zones."

Another Infected variant has all the players begin as Juggernauts only armed with .44 magnums dual wielded, Scavenger Perk, and nothing else. As before, when the timer is up one player becomes the infected, and gains the Infect loadout: Striker, XM25, Semtex, Tactical Insertion, Sleight of Hand, Quickdraw, Steady Aim, and Dead Man's Hand, while keeping the Juggernaut suit. After one kill he loses his Juggernaut suit, but retains the loadout. As usual, the Juggernauts must kill the Infected; if any Juggernaut is slain he will transfer to the Infected team. The Juggernauts win if at least one person can hold out until the time is up; otherwise victory is forfeited and the infected win. It is also impossible to hide in this loadout, since the map is always very small, and the Infected radar always shows the Juggernaut icon.

Call of Duty: Ghosts
Infected returns in Call of Duty: Ghosts. It plays similarly to the Modern Warfare 3 variant, with the same objective and the Infected receiving Tactical Insertions and Throwing Knifes. At the start of the game, players have 15 seconds until one of the 12 Survivors (18 on Xbox One, PC and Playstation 4) turns into an infected. Instead of a Combat Knife, the first Infected will sport a selected weapon (primarily the M9A1 pistol) until he claims his first victim. Once the First Infected is selected, he has two minutes to infect the first Survivor. All survivors spawn with the Scavenger perk and a Specialist strike package. With each Survivor turned into an Infected, the timer will reset back to two minutes. This means an Infected match could last up to 22 minutes if the Survivors are not killed fast enough. When there is one Survivor left, a radar sweep will occur every 30 seconds. Since Survivors do not have Off the Grid (except in Infected Lynx by getting 5 kills), their death is inevitable, regardless of how well they hide.

Survivors use their current customized renders while the Infected are rendered with a tan hooded jacket.

Call of Duty: Advanced Warfare
Infected returns in Call of Duty: Advanced Warfare. It is mostly the same as in Call of Duty: Ghosts except the loadout is a random primary weapon and the abilities of the Exoskeleton. Infected players are given a unique hazmat suit, while survivors are given their currently-selected custom operator.

Knife vs. Striker

 * Primary Weapon: Striker (Extended Mags with Damage Proficiency)
 * Secondary Weapon: Five Seven (Akimbo)
 * Lethal Item: C4
 * Tactical Item: None
 * Perks: Scavenger, Hardline, Steady Aim
 * Rewards: Sleight of Hand, Quickdraw, Dead Silence
 * Bonus Perks: None
 * Death Streak: None

Knife vs. PP90M1

 * Primary Weapon: PP90M1 with Kick Proficiency)
 * Secondary Weapon: .44 Magnum (Akimbo)
 * Lethal Item: Claymore
 * Tactical Item: None
 * Perks: Scavenger, Quickdraw, Stalker
 * Rewards: Sleight of Hand, Dead Silence, Steady Aim
 * Bonus Perks: None
 * Death Streak: None

Knife vs. FMG-9

 * Primary Weapon: None
 * Secondary Weapon: FMG-9 (Akimbo)
 * Lethal Item: C4
 * Tactical Item: None
 * Perks: Scavenger, Hardline, Steady Aim
 * Rewards: Sleight of Hand, Quickdraw, Dead Silence
 * Bonus Perks: None
 * Death Streak: None

Knife vs. Type 95

 * Primary Weapon: Type 95 (With Red Dot Sight)
 * Secondary Weapon: .44 Magnum (Akimbo)
 * Lethal Item: Claymore
 * Tactical Item: None
 * Perks: Scavenger, Quickdraw, Stalker
 * Rewards: Sleight of Hand, Dead Silence, Steady Aim
 * Bonus Perks: None
 * Death Streak: None

Knife vs. Barrett

 * Primary weapon: Barrett .50 Cal (Attachments proficiency providing Extended mags and Heartbeat sensor)
 * Secondary Weapon: Five Seven (Akimbo)
 * Lethal Item: Bouncing Betty
 * Tactical Item: None
 * Perks: Sleight of Hand, Hardline, Steady Aim
 * Rewards: Quickdraw, Assassin, Marksman
 * Bonus Perks: Scavenger (Survivors do not start with extra ammo the Pro variant provides. They must acquire a blue pack after every kill to keep themselves supplied.)
 * Death Streak: None

Striker vs. Jugg

 * Primary Weapon: None
 * Secondary Weapon: .44 Magnum (Akimbo )
 * Lethal Item: None
 * Tactical Item: None
 * Perks: Scavenger
 * Rewards: None
 * Bonus Perks: None
 * Death Streak: None
 * Juggernaut Suit Enabled

Jugg vs. MK46 (Removed)

 * Primary Weapon: MK46 with Kick Proficiency
 * Secondary Weapon: RPG-7
 * Lethal Item: Claymore
 * Tactical Item: Smoke Grenade
 * Perks: Scavenger, Quickdraw, Steady Aim
 * Rewards: None
 * Bonus Perks: None
 * Death Streak: None

Knife vs. .44 Magnum (Removed)

 * Primary Weapon: None
 * Secondary Weapon: .44 Magnum with Akimbo
 * Lethal Item: C4
 * Tactical Item: Concussion Grenades
 * Perks: Scavenger, Quickdraw, Steady Aim
 * Rewards: None
 * Bonus Perks: None
 * Death Streak: None

Default

 * Primary Weapon: None
 * Secondary Weapon: Empty USP .45 with Tactical Knife
 * Lethal Item: Throwing Knife
 * Tactical Item: Tactical Insertion
 * Perks: Extreme Conditioning and Quickdraw, Dead Silence granted in some cases
 * Rewards: None
 * Bonus Perk: Either Marathon, Lightweight or both. Grants a speed boost similar to the effects of Juiced
 * Death Streak: Juiced

Striker vs. Jugg

 * Primary: Striker with Extended Mags and Range proficiency
 * Secondary: XM25
 * Lethal Item: Semtex
 * Tactical Item: Tactical Insertion
 * Perks: Sleight of Hand, Quickdraw and Steady Aim
 * Rewards: None
 * Bonus Perk: None
 * Death Streak: Dead Man's Hand

Jugg vs. MK46 (Removed)

 * Primary: None
 * Secondary: Empty USP .45 with Tactical Knife
 * Lethal Item: Throwing Knife
 * Tactical Item: Tactical Insertion
 * Perks: Extreme Conditioning, Quickdraw, Dead Silence
 * Rewards: None
 * Bonus Perk: None
 * Death Streak: Juiced
 * Juggernaut Suit Enabled

"First Infected"
The game starts with a nine second countdown where a random player becomes the "First Infected". Once the first player becomes infected, he doesn't start out with the knife loadout, but rather at first uses the current Survivor loadout (example: the first Infected will still be holding his Striker), however, it comes with the Throwing Knife, Tactical Insertion, and the Infected Perks. Their Death Streak is Hollow Points. The First Infected uses the gun to infect a second person. Once this is achieved, the Infected will then use their knife loadout for the remainder of the match.

In the case of the Barrett loadout, the First Infected will use an ACR 6.8 w/ Silencer and Red Dot Sight to give an edge in Infecting the next victim, since it is more effective than attempting to spray and pray, or even attempt to quickscope a second victim. In "Striker vs Jugg", the first infected will receive a Juggernaut Suit. In "Jugg vs MK46", they will receive an MK46 with Extended Mags.

When there are only two Infected, if one of them leaves, then the other becomes "First Infected" again, and must infect another player to continue the cycle and the game.

Infected Bulldog

 * Primary Weapon: Bulldog
 * Secondary Weapon: None
 * Equipment: I.E.D., Concussion Grenade
 * Perks: Marathon, Dead Silence, Scavenger
 * Specialist Package: None
 * First Infected is given the M9A1

Infected MTS

 * Primary Weapon: MTS-255 w/ Red Dot Sight and Muzzle Brake
 * Secondary Weapon: P226 w/ Akimbo
 * Equipment: I.E.D.
 * Perks: Sleight of Hand, Steady Aim, Scavenger, Hardline
 * Specialist Package: Quickdraw, Reflex, Dead Silence, Ping (Specialist Bonus)
 * First Infected is given the M9A1

Infected PDW

 * Primary Weapon: Combat Knife
 * Secondary Weapon: PDW w/ Extended Mags
 * Equipment: C4
 * Perks: Strong Arm, Steady Aim, Scavenger, Extra Lethal, Hardline
 * Specialist Package: Sleight of Hand, Quickdraw, Dead Silence
 * First Infected is given the M9A1

Infected MSBS

 * Primary Weapon: MSBS w/ Red Dot Sight
 * Secondary Weapon: .44 Magnum
 * Equipment: I.E.D.
 * Perks: Ready Up, Stalker, Quickdraw, Scavenger
 * Specialist Package: Sleight of Hand, Reflex, Dead Silence
 * First infected is given the M9A1

Infected Lynx

 * Primary Weapon: Lynx w/ Extended Mags
 * Secondary Weapon: M9A1 w/ Akimbo
 * Equipment: I.E.D.
 * Perks: Sleight of Hand, Scavenger, Focus, Hardline
 * Specialist Package: Quickdraw, Reflex, Off the Grid
 * First Infected is given the M9A1

Infected Riot

 * Primary Weapon: Riot Shield w/ Titanium Frame
 * Secondary Weapon: .44 Magnum w/ Akimbo
 * Equipment: I.E.D.
 * Perks: Ready Up, Sleight of Hand, Scavenger, Resilience, Hardline
 * Specialist Package: Steady Aim, Reflex, Dead Silence
 * First Infected is given the Bulldog; Remaining Infected are given a Semtex instead of Throwing Knife.

Infected Loadout

 * Primary Weapon: Combat Knife
 * Secondary Weapon: None
 * Lethal: Throwing Knife (Semtex on the Riot loadout)
 * Tactical: Tactical Insertion
 * Perks: Resilience, Dead Silence (Sometimes), Marathon

Survivor

 * Primary Weapon: Random
 * Secondary Weapon: None
 * Exo Ability :  Exo Shield
 * Exo Launcher: Explosive Drone
 * Perk 1: Scavenger

Initial Infected

 * Primary Weapon: RW-1
 * Secondary Weapon: Combat Knife
 * Exo Launcher: Spike Drone
 * Exo Ability: Tactical Insertion

Infected

 * Primary Weapon: Combat Knife
 * Secondary Weapon: None
 * Exo Launcher: Spike Drone
 * Exo Ability: Tactical Insertion

Final Survivor
When there is one Survivor left, that player will be notified as "Final Survivor". The Infected have the rest of the game to search the entire map for the last Survivor. Sometimes the Survivor would be hiding in a patch of grass in a place that is mostly overlooked, so the Infected have to make sure they look at every piece of scenery and environment around every corner of the map (it is particularly very difficult in the Barrett loadout, especially if the Survivor is wearing a Ghillie Suit). On occasions, the Survivor will be making his last stand on the popular camping spots of the maps, and if the map is small, (such as the catwalks on Dome, or the street side of Underground), the Infected simply have to swarm the survivor.

When the Survivor has not been located for a while, a radar pings every 10-15 seconds, showing the red dot where he is hiding. If the Survivor has earned Assassin (via Specialist Bonus), the radar effect is negated and he won't appear on the minimap. If the MOAB has been activated, the radar is useless for the 60 seconds it is active.

If there are fewer than 17 Infected (12 in Call of Duty: Ghosts on PS3, Xbox 360, and Wii U, and Call of Duty: Advanced Warfare on all consoles, except the Wii U) and a Final Survivor, should a new player connect into the lobby, the connecting player becomes a new Survivor and the radar scan is disabled until only the Final Survivor remains. This poses a problem for the Infected who are already searching hard for the Final Survivor, only to find out an anonymous Survivor has entered the game and delayed their victory, or when the "final" Survivor has finally been killed, the game still hasn't ended because a new Survivor has just connected. This could be frustrating especially when the game is coming down to the final seconds, the new Survivor connects and just hides long enough for the game to end, thus the Survivor wins.

Death zones
These are a list of "death zones" that are present in public infected. These zones automatically kill the player regardless of being a survivor or infected. This is to eliminate certain areas that would otherwise give a survivor an unfair advantage, usually due to them being out of reach of the infected.
 * The van in the loading dock in Arkaden.
 * The signpost in Underground, just after a window where the destroyed trains are.
 * The signpost in Resistance, leading to the magazine stall.
 * The top of some roofing, just near the Black Hawk, as well as the top of the downed Black Hawk in Bakaara.
 * The potted bush, opposite of the top of the escalators in Arkaden.
 * The edge of a building roof in Seatown, near the restaurant in the far south-east corner of the map.
 * The propane tanks sitting on a truck bed near the yellow bulldozer in Hardhat.
 * The barrels behind the fenced forklift vehicle in the middle of Hardhat.
 * The lamp post near the top left of Downturn, just near the destroyed fire engine.
 * The crane basket near the top right of Downturn.
 * The ledge in the bottom left of Downturn, just next to the Marley and Griffin trucks.
 * There are kill zones beyond a "barrier" below the broken steel window of the southwest ship in Decommission - sometimes, some players still manage to get over and into the seemingly impossible ledge in the corner down there. Because the last Survivor who knows this glitch tends to camp there, the rest of the Infected would always crowd in there, making it extremely difficult to reach in there and even more difficult to attempt a Throwing Knife.
 * The top of a partially open garage door near the A flag on Fallen, normally accessible by jumping from the railing on the walkway of the adjacent building.

General

 * Survivors can become infected without an Infected killing them. This happens from committing suicide, entering a death zone, or falling from too great a height, like the well in Seatown, or the wooden bridge in Mission; or if they blow themselves up with C4.
 * A Host Migration can occur if the "First Infected" ends the game before infecting another player, thus causing the network to reboot and randomly select another "Infected".
 * The playlist has been updated multiple times such as: adding Throwing Knife, Specialist Strike Package; taking out game modes such as MK46 vs Jugg; removing Tactical Grenades, etc.
 * In both games, when a player is infected and leaves the game, then rejoins, they will be put on the infected team again rather than being a survivor. This however, can be changed, for if the user changes their clan tag and rejoins, they will be on the Survivors side.

Call of Duty: Modern Warfare 3

 * In "Striker vs Jugg", the First Infected will have black armor.
 * While playing online, though the Infected are sometimes listed to have no third perk, they do not suffer from falling damage, as if they had Dead Silence Pro, though their foot steps can nevertheless be heard. Also, the Featherweight challenges can be achieved this way, even if the player does not have said perk. However, Dead Silence only appears in the "Barrett" loadout and actually silences their footsteps.
 * The PP90M1 originally had extended mags, but was later removed.
 * This game mode is unavailable for the Wii.
 * Unlike other game modes, in which kills scored by a Juggernaut show up with the Jugg killfeed, "Striker vs Jugg" will show the actual weapon with which the Infected was killed.

Call of Duty: Ghosts

 * In Call of Duty: Ghosts, the Tactical Insertion the Infected use looks like a different and low quality model. It is possible this was a placeholder model of the Tactical Insertion before it was removed from the other Multiplayer playlists.
 * In Call of Duty: Ghosts, in Private Match, the player can now change the loadouts, thanks to a patch released on 28th January 2014.

Call of Duty: Advanced Warfare

 * The Bulldog was originally the starting weapon at all times, but then it was changed to being a random primary weapon.
 * In Private Match, if the player adds scorestreaks to the preset class the Survivors team uses, they will not show up in the player's loadout during gameplay and cannot be earned.
 * People can kill their own teammates when deploying explosive drones. However, it is difficult because they need to shoot the right spot of the explosive drone in order to kill their teammates and themselves.