CRYPTOSPORIDIOSIS IN ADULTS IN LUSAKA, ZAMBIA, AND ITS RELATIONSHIP TO OOCYST CONTAMINATION OF DRINKING-WATER

In Lusaka, where human immunodeficiency virus seroprevalence in young adults is similar to 25%, four townships were studied to establish the prevalence of persistent diarrhea in adults and the etiologic importa nce of cryptosporidiosis in adults with persistent diarrhea. Cryptospo ridium parvum oocyst contamination of urban water supplies was measure d and the results used to categorize these populations into high or lo w exposure. In total, 506 adults were reported as having had diarrhea in the 2 weeks prior to the survey; 101 of these episodes were persist ent. Adults with persistent diarrhea in the high-exposure areas were m ore likely to have cryptosporidiosis (odds ratio, 5.14; 95% confidence interval, 1.57-17.2; risk ratio, 1.83; 95% confidence interval, 1.04- 3.21; P =.003) although overall prevalence of persistent diarrhea was not greater in these areas. This association was not confounded by ani mal exposure, travel, or boiling water. Within these urban populations , water contamination with C. parvum was a major influence on the prev alence of infection.