Contagion is a passive item in The Binding of Isaac, added in the Afterbirth+ DLC.

The first enemy killed in each room will release a gas explosion that poisons nearby enemies.

Enemies poisoned by this explosion will also release gas upon death, spreading the effect.

Poisoned enemies don't have to die while poisoned in order for the gas explosion to take place.

The initial gas explosion deals 5 damage, and the poison deals Isaac's tear damage per tick for 6 total ticks.

This page shows the latest information as of the new Repentance+ (Online Co-op) DLC.
To see information about this item for the previous Repentance version, check this page instead.

Contagion can be found in the following item pools:

The following tags are applied to this item:

The following special synergies and interactions for Contagion have been documented.

* Note that not all possible synergies and interactions are listed here.

Below is the Internal Item Description as shown in-game.
Note that some stat changes are not displayed here. Please see the main description for the full effects.

Contagion

• The first enemy killed in each room explodes and poisons nearby enemies
• Poisoned enemies also explode on death, spreading the poison to more enemies
• Abyss: x1 poison locust 1x Isaac's damage

• Check out the item description on the external Isaac Wiki.