Fever or unknown origin in HIV/AIDS patients.

Fevers of unknown origin (FUO) in HIV/AIDS patients are due to the same infectious causes that are common in this subset of compromised hosts but manifest clinically as prolonged fevers. In North America, the most common etiologies of FUO in HIV/AIDS are due to intracellular pathogens, i.e., disseminated Mycobacterium avium-intracellulare, Pneumocystis carinii pneumonia (PCP), fungi or cytomegalovirus. Worldwide, leishmaniasis and Mycobacterium tuberculosis are the most important. Infections presenting as FUOs in the HIV population occur only in the late stages of illness when the CD4 count is < 100.