Organisms of the Mycobacterium avium complex cause disseminated infections in
25 to 50 % of patients with AIDS. To assess the likelihood of exposure to M avium, we
attempted to recover M. avium complex from environmental samples in geographical areas
(Boston, Massachusetts; Hanover, New Hampshire; Helsinki, Finland; Nairobi, Kenya;
and Kinsasha, Zaire) located near M. avium infected AIDS patients. Although M. avium
was recovered from environmental samples at all sites, it was found more frequently in
water supply systems in the United States and Finland (8/25, 32 %) compared to water
supply samples from Africa (0/14, 0%).
To determine if M. avium isolates recovered from the same geographical area as
AIDS patients shared phenotypic and genetic characteristics with clinical AIDS M. avium
isolates (recovered by collaborating laboratories), the ability to grow at 43°C, cadmium-and streptomycin-resistance, and the presence of plasmids were used as epidemiological
markers. We found that environmental isolates in this study shared similar characteristics
with the clinical AIDS M. avium isolates.
Compared to developed countries, the prevalence of M. avium infections among
AIDS patients in developing countries (i.e., Africa) is very low. To determine if M. avium was absent in the African environment, we attempted to recover the organisms
from water and soil in Kampala, Uganda. M. avium was recovered from 43 % of
environmental samples, and these isolates shared similar phenotypic and genetic
characteristics with M. avium isolates from the United States.
Cigararette smoking was identified as a possible risk factor for HIV infected
individuals. M avium isolates were recovered from several brands of cigarettes,
suggesting that cigarettes are a possible source of infection.
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