Mycotics are humans who are infected with RFG (Rapid Fungal Growth). Mycotics are extremely aggressive, causing them to attack anyone nearby. They suffer from seeing illusions of people they love and care about taunting them, causing the aggression. Mycotics normally only live 72 hours; however, it is revealed in Vade in Pace that mycotics can live longer (one mycotic living up to 5 days), by consuming the sap from the "Bleeding Tree." The sap appears to have a "calming" effect on mycotics, and prevents them from getting sicker.
Two mycotics were cannibals eating non-infected humans. They did not eat their own, saying it was, "wrong, what do you take us for, savages?". The fungus makes the flesh taste rotten.
The word Mycotic comes from a fusion of the words mycosis (fungus) and psychosis/psychotic.