The incidence of cryptosporidiosis: a two-year prospective survey in a children's hospital.

A two-year prospective survey of patients with diarrhoea at a children's hospital detected 65 cases of cryptosporidiosis; 56 were index cases representing 1.4% of patients examined. There was a marked seasonal variation with fewer index cases in July-September (0.4-0.6%) than February-April (3-5%). All four adult cases were contacts of infected children and 21 (32%) of the patients were 12 months old or younger. Cryptosporidium was the fourth commonest diagnosed cause of gastroenteritis, the second most common non-viral cause, was responsible for 7.2% of all cases, and 14.7% of non-viral cases where a cause was identified. As such it should be sought routinely in cases of gastroenteritis in children.