What is the prevalence of mycobacterium avium complex (MAC) (mycobacterium avium-intracellulare [MAI]) infections in the US?

Updated: Oct 17, 2019
  • Author: Janak Koirala, MD, MPH, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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NTM infections began to be reported more frequently after the incidence of tuberculosis declined in the 1950s. During 1979-80, NTM represented one third of mycobacterial isolates reported to the Centers for Disease Control and Prevention (CDC), and 61% of these were MAC. MAC and Mycobacterium kansasii are two of the most predominant NTM infections in the United States .

In the United States, MAC infection is considered a nonreportable infectious disease. However, CDC surveillance data from Houston and Atlanta suggest an incidence of 1 case per 100,000 persons per year. [15] A 2009 study in Oregon estimated an annualized rate of 5.6 cases of MAC pulmonary infection per 100,000 population, with most cases (60%) affecting females. [16] One case series revealed cutaneous involvement in 6 of 30 cases of DMAC infection.

DMAC is the most common mycobacterial infection in patients with advanced AIDS. The overall prevalence of DMAC infection increased in the 1980s and early 1990s in the United States following the advent of HIV and AIDS. The highest incidence of DMAC, 37,000 cases, was measured in 1994, at the peak in the AIDS epidemic.

The incidence of DMAC has declined since the adoption of highly active antiretroviral therapy (HAART). Prior to the widespread use of combination antiretroviral therapy (ART), 30% of patients infected with HIV developed DMAC infection, whereas in a 1996 study, only 2% of patients receiving HAART, including a protease inhibitor, developed DMAC infection. The decrease in DMAC may also reflect the use of antimicrobial prophylaxis in HIV-infected patients.

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