Abstract
Mycobacterium avium complex (MAC) is a ubiquitous organism. Human infection with this agent causes one of three clinical syndromes: pulmonary disease in persons whose systemic immunity is intact; cervical lymphadenitis, also a disease of normal hosts; and disseminated disease, usually in persons with advanced human immunodeficiency virus infection. While data are sparse, all three clinical syndromes appear to be increasing in frequency. However, the environmental reservoirs and modes of acquisition of MAC have not been elucidated. and strategies for avoidance of MAC infection remain to be defined.