Effectiveness of Rotavirus Immunization in Nicaragua

The purpose of the investigators study is to compare the rates of childhood diarrhea at the community level before and after the rotavirus vaccination program in León, Nicaragua. From preliminary studies, the investigators anticipate about a 28% reduction in diarrhea following the vaccination program among children who received the vaccine, and a smaller reduction in diarrhea among children who did not receive the vaccine, due to the effects of "herd immunity". In addition, the investigators will collect stool samples from children who develop diarrhea in order determine the etiology of childhood diarrhea in the post-rotavirus immunization era.