Biliary Cryptosporidiosis in HIV-Infected People after the Waterborne Outbreak of Cryptosporidiosis in Milwaukee

BACKGROUND: In March 1993, the municipal water supply in Milwaukee became contaminated with cryptosporidium and a widespread outbreak of cryptosporidiosis occurred. METHODS: We retrospectively studied the relations among the clinical presentation, CD4 count, and survival in a group of 82 patients infected with the human immunodeficiency virus (HIV) in whom cryptosporidiosis developed during the outbreak. Infection was documented by the finding of cryptosporidium in stool. RESULTS: There was a sharp increase in the number of HIV-infected patients with cryptosporidiosis after the period of water contamination. Four of 24 patients with biliary symptoms (17 percent) and 30 of 58 without biliary symptoms (52 percent) were alive one year after the outbreak (P = 0.003). Twenty-one of the patients with biliary symptoms had CD4 counts < or = 50 per cubic millimeter, as compared with 36 of 57 patients without biliary symptoms (88 percent vs. 63 percent, P = 0.03). The CD4 count was not available for one patient in the latter group. Within one year, 41 of the patients with CD4 counts < or = 50 per cubic millimeter had died, as compared with 6 of those with higher counts (72 percent vs. 25 percent, P < 0.001). After adjustment for the CD4 count, independent predictors of death were older age and the presence of nausea and vomiting. CONCLUSIONS: When HIV-infected patients are exposed to cryptosporidium, those with CD4 counts < or = 50 per cubic millimeter are at increased risk for biliary symptoms and for death within one year after the infection.