Addon: Baby Parasites
Author: xiaocraft

Parasite development
Thirteen host types can pass through two stages of infection, creating twenty-six hostile variants. Different bodies and behavior make the outbreak more varied than a single replacement mob.

Corrupted land
Infection changes nearby terrain and allows carnivorous plants to appear. Contaminated areas therefore become more dangerous over time and can threaten established bases.

Protection and treatment
Hazard armor helps the player enter infected zones. A Serum Bag can cure affected creatures, while the in-game guide explains the main survival mechanics.
How to install the add-on
Download the .mcaddon or .mcpack file, open it with Minecraft and wait for the import to finish. Then enable the resource and behavior packs in the world settings. If the add-on requires experiments, turn them on before launching the world.