Cryptosporidium and cryptosporidiosis.

Cryptosporidium is a newly recognized human pathogen associated with severe enteritis and, perhaps, cholecystitis in immunocompromised patients, particularly those with the acquired immunodeficiency syndrome, and significant, though self-limited, diarrheal illness in the immunocompetent host. As more physicians look for this pathogen, the number of reported cases of cryptosporidiosis continues to increase. Although the prevalence of cryptosporidiosis in humans is not yet known, recent studies suggest that it is a common cause of diarrhea worldwide, particularly in young children. The pathogenic mechanisms by which Cryptosporidium causes enteritis and the factors of human host defense essential for eradication of this parasite have not been delineated. Acid-fast staining of stool is a quick and reliable way of diagnosing cryptosporidiosis. Although a vast array of therapeutic agents has been tried for this disease, there is currently no known effective therapy for cryptosporidial infection.