Risk factors for intestinal microsporidiosis in patients with human immunodeficiency virus infection: a case-control study.

A prospective unmatched case-control study was conducted to determine risk factors for intestinal microsporidiosis in persons infected with human immunodeficiency virus (HIV) who had < or = 200 CD4 cells/mm3. In multivariate analysis, case-patients (n = 30) were more likely than were control-subjects (n = 56) to have < or = 100 CD4 cells/mm3 (odds ratio [OR], 6.5; 95% confidence interval [CI], 1-42), to report male homosexual preference (OR, 7.6; 95% CI, 1-59.5), and to report swimming in a pool in the previous 12 months (OR, 9.2; 95% CI, 2.1-38.9). In summary, intestinal microsporidiosis in persons with HIV infection and < or = 200/mm3 CD4 cells is associated with male homosexuality and swimming in pools, suggesting fecal-oral transmission, including sexual and waterborne routes.