What is cordyceps?

1) A fungal parasite that infects ants and other insects commenly found in rainforests
2) a fungal infection featured in the hit game the last of us similar to a zombie virus there are 4 stages of infection runners, stalkers, clickers and bloaters if the infected person dies the body spouts fungal spores to help spread the infection however people who are immune (ellie) dont have to wear gas masks