RESUMEN
BACKGROUND AND OBJECTIVE: On the basis of several cases of cryptosporidiosis detected in a child day-care center, we stablished the extent of the outbreak and investigated causes of parasite transmission. PATIENTS AND METHOD: A retrospective cohort study was designed on all children attending day-care center and care givers to determine their infection status and identify risk factors associated to the outbreak. RESULTS: 24 cases of cryptosporidiosis were detected, with an attack rate of 0.46 (24/52); 12 of them were parasitologycally confirmed. All care givers were negative for Cryptosporidium and none of them reported symptoms of acute gastroenteritis. Transmission pattern was compatible with person to person modes. Among the factors investigated, two were associated with the risk of disease: diaper wear (relative risk = 2.06; p = 0.059); and diarrhea in relatives (relative risk = 2.05; p = 0.01). In all confirmed cases, Cryptosporidium hominis (previously known as C. parvum, genotype 1), was identified. CONCLUSIONS: Cryptosporidiosis should be considered as a possible cause of outbreaks of gastroenteritis at day-care centers. Increasing care on diaper changing practices, specially over children with diarrhea, may be the key factor to prevent transmission of Cryptosporidium.