The Last of Us Part II is an action-adventure game developed by Naughty Dog and published by Sony Interactive Entertainment. It's set five years after The Last of Us (2013) and, as its predecessor, focuses on storytelling and immersion into the post-apocalyptic United States. The outbreak was nearly 25 years ago and was caused by a mutated strain of the Cordyceps fungus, that can infect humans. It grows in the brain and slowly starts to take control over the host, turning it into a zombie-esk creature, called the infected.

The earlier stage of the Cordyceps brain infection (abbreviated as CBI) infection. The sounds they make are still human and the difference of male and female specimen is audible.