Infection with C. neoformans is termed cryptococcosis and most infections consist of a lung infection. However, fungal meningitis and encephalitis, especially as a secondary infection for AIDS patients, are often caused by C. neoformans making it a particularly dangerous fungus. Infections with this fungus are rare in those with fully functioning immune systems. For this reason, C. neoformans is sometimes referred to as an opportunistic fungus. It is a facultative intracellular pathogen.