Asymptomatic respiratory tract microsporidiosis due to Encephalitozoon hellem in three patients with AIDS.

Microsporidia of the genera Enterocytozoon and Encephalitozoon have been identified as frequent causes of intestinal and disseminated infections, respectively, in patients with AIDS. Even though most subjects infected with these protozoa develop overt disease, simple colonization without illness may occur, as we observed in three severely immunosuppressed patients with AIDS. The parasites, recognized in and isolated from bronchoalveolar lavage sediment specimens, were characterized as Encephalitozoon hellem. Colonization of the bronchial tree was temporary, and treatment with albendazole was not needed to clear the infection.