Environmental Risk Factors for Acquisition of Mycobacterium Avium Complex in Persons with Human Immunodeficiency Virus Infection

A case-control study was done to determine risk factors for Mycobacterium avium complex (MAC) disease in persons infected with human immunodeficiency virus (HIV) with < 50 CD4+ cells/mm3. In univariate analysis, cases (n = 83) had lower CD4+ cell counts than controls (n = 177) (median, 10 vs. 17/mm3; P < .001) and were more likely to have consumed hard cheese (odds ratio [OR], 5.44; 95% confidence interval [CI], 1.61-18.4) but were less likely to have taken daily showers (OR, 0.55; 95% CI, 0.33-0.94). In multivariate analysis, CD4+ cell count < 25/mm3 (OR, 3.58; 95% CI, 1.71-7.49) and consumption of hard cheese (OR, 5.63; 95% CI, 1.58-20.1) remained associated with disease, while daily showering (OR, 0.58; 95% CI, 0.28-0.88) remained protective. Increased risk for MAC disease in persons with HIV infection and low CD4+ cell counts is not associated with exposure to water or a variety of other environmental sources but may be associated with consumption of hard cheese.