Mycobacterium Avium Complex
(MAC) Disease

Mycobacterium Avium Complex (MAC) is a family of opportunistic bacterial pathogens related to mycobacterium tuberculosis that are found almost everywhere in our environment, including food, water and soil.

Incidence; Contributing Risk Factors

The prevalence of MAC disease was 1.1 per 100,000 in the pre-AIDS era and these cases were most often recognized in persons with underlying lung disease.

Some types of MAC bacteria cause disease, primarily in individuals with compromised immune systems but also rarely in individuals without identified susceptibilities.

Potentially, water is a route of exposure to MAC through ingestion and inhalation of aerosols.  However, given a lifetime of exposure to a ubiquitous agent and the limited number of individuals with recognized disease, the lifetime risk from MAC for the normal immunocompetent host is negligible.