Severe cryptosporidiosis in an immunocompetent host.

Cryptosporidiosis is increasingly recognized as a significant human pathogen. Previous reports have emphasized the benign, self-limited nature of the illness in the immunocompetent adult. In contrast, immunodeficient hosts have severe, frequently unremitting illness. We describe a case in which an individual, with no evidence of immunodeficiency and negative human immunodeficiency virus serologic findings, was admitted with a five-week history of severe diarrhea, marked weight loss, and renal failure probably as a consequence of cryptosporidiosis. The patient's renal function returned to normal with hydration, and his diarrhea resolved without specific therapy. At a six-month follow-up, the patient was in excellent health.