Diarrheal disease studies in Costa Rica. I. Plan and methods of investigation.
D000818:Animals; D003364:Costa Rica; D003968:Diarrhea, Infantile / Q000453:epidemiology*; D004812:Epidemiologic Methods; D005513:Food Inspection; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn