Pneumocystis carinii

…rare lung infection known as Pneumocystis carinii pneumonia in five homosexual men in Los Angeles. Expert review of the cases suggested that the disease likely was acquired through sexual contact and that it appeared to be associated with immune dysfunction caused by exposure to some factor that predisposed the affected…

Pneumocystis carinii causes pulmonary disease in immunocompromised patients. These infections are treated with trimethoprim-sulfamethoxazole, which inhibits folic acid synthesis in protozoans. An alternative agent for treatment of these diseases is pentamidine isethionate, which probably affects the parasite by binding to DNA.

…and protozoan parasites (such as Pneumocystis carinii) are common in patients receiving immunosuppressive drugs or in patients with cancer, AIDS, or other chronic diseases. Pneumocystis carinii pneumonia has been one of the major causes of death among AIDS patients.