Contagion

Contagion is a passive item added in The Binding of Isaac: Afterbirth †.

Effects

 * In each room, the first enemy killed will release a gas explosion and poison nearby enemies.
 * Poisoned enemies will also release gas upon death, spreading the effect.
 * Poisoned enemies do not need to die while the poison is still active to spread the effect.
 * The effect will also activate if a shopkeeper is destroyed before killing any enemies.
 * Re-entering a room and destroying another shopkeeper inside it will trigger the effect for a second time.

Interactions

 * : Bomb damage does not apply to poison damage.
 * : Missile damage does not apply to poison damage.
 * : Ipecac only applies a 2x multiplier as opposed to +40 to poison damage.
 * Poison tears: No effect. Gas explosions will only be triggered by poison caused by Contagion
 * Second Hand: Poison duration is not affected.

Trivia

 * Its sprite is a recolor of.
 * This item may be a reference to the movies Contagion and Outbreak, or the game Plague Inc..