Methods: A randomized clinical trial, controlled, double-blind. The investigators will have two groups of patients : One group will receive Lactobacillus Rahmnosus in a yogurt presentation and the other one will receive Sacharomyces boulardii in a lyophilized form ; the parameters of evaluation are going to be the number of diarrhea stools by day, number of vomiting episodes, hours with fever, nutritional and immunization state.