Cryptosporidiosis in Immunocompetent Patients

The intestinal protozoan cryptosporidium is known to cause diarrhea in immunocompromised patients, but few cases have been reported in detail in immunocompetent persons. During a 12-month period, we identified cryptosporidium in the stools of 43 immunocompetent patients. The numbers of cases were increased in those under 4 years old and in those from 30 to 39 years old. Of 30 index cases, 23 (77 per cent) were diagnosed in the late summer or the fall. Fifteen of the 43 patients (35 per cent) had other gastrointestinal pathogens, of which only Giardia lamblia was statistically associated with cryptosporidium. In the 28 patients in whom other gastrointestinal pathogens were not identified, the clinical manifestations were predominantly watery, nonbloody diarrhea and, less commonly, abdominal discomfort, anorexia, fever, nausea, and weight loss. The infection was self-limited in all 43 patients. Clustering of cases occurred in a day-care center and in two families. These clinical observations confirm worldwide findings and suggest that cryptosporidium is a relatively common nonviral cause of self-limited diarrhea in immunocompetent persons in the northeastern United States. (N Engl J Med 1985; 312:1278–82.) The intestinal protozoan cryptosporidium is a well-known cause of gastroenteritis in animals and has recently been shown to cause a similar illness in human beings. 1 2 3 4 The organism was initially described on the gastric mucosa of asymptomatic mice in 1907, 5 but was not associated with disease in animals until 1955, when Slavin 6 reported diarrheal illness in turkeys. Subsequently, cryptosporidium was found to cause disease in calves, lambs, pigs, and other domestic and wild animals. 1 2 3 The first case of human infection was reported in 1976, 7 and only seven additional cases were documented before 1982. 1 Since then, the number of cases identified has . . .