Microsporidiosis is a rapidly emerging protozoon infection that has been reported predominantly in severely immunosuppressed persons with acquired immunodeficiency syndrome (AIDS). Since the first case of human microsporidian infection was reported in 1956, over 400 cases have been documented. The initial description of microsporidian infection in AIDS patients occurred in 1985. Five genera have been identified as the agents of microsporidiosis in immunocompromised persons (Enterocytozoon, Encephalitozoon, Septata, Pleistophora and Nosema). Respiratory tract infection due to microsporidia is associated almost exclusively with disseminated disease produced by members of the genera Encephalitozoon and Septata. Metronidazole and albendazole were recently reported to be responsible for clinical improvement of patients. The authors reported a case of a woman with AIDS and respiratory symptoms related to two pulmonary pathogens: Mycobacterium tuberculosis and Encephalitozoon cuniculi, identified by polymerase chain reaction (PCR) using diagnostic primers targeting the small subunit ribosomal RNA.

Keywords: Microsporidiosis. Respiratory tract infection. Acquired immunodeficiency syndrome.