Asymptomatic salmonellosis among children in day-care centers in Mérida, Yucatan, Mexico.

Abstract

Child day-care centers (DCC) have become common in many lower and middle income countries, presenting new problems that may differ from those of DCC in more developed countries. Diarrhea is a common problem in DCC in the United States, but information on the prevalence of diarrhea or specific enteropathogens among children in DCC in tropical and developing countries is limited. Because of preliminary data from newborns and DCC attendees in Mérida, Mexico, with high rates of Salmonella infection, we conducted a 12-month longitudinal surveillance study of enteropathogens in two Mérida DCC. Seventy-eight children ages 2 months to 4 years were evaluated with demographic and clinical data, and stools were cultured monthly. Salmonella sp. was the most common enteropathogen detected (46 of 683 specimens, 6.7%), with higher rates in children younger than 18 months (P < 0.02), but it was found in only 1 of 10 diarrhea episodes that coincided with sampling. Other common organisms identified included Giardia lamblia (21 of 683, 3.0%) and LT-producing enterotoxigenic Escherichia coli (16 of 683, 2.3%). Salmonella was recovered from as many as 19% of children in a single month, but the large multiplicity of serotypes recovered suggested multiple sources rather than a common source outbreak. Children with Salmonella tended to have more liquid stools during the preceding 2 weeks. Salmonella was also isolated from the stool of teachers in 1 of the 2 DCC in 10 of 94 specimens (10.6%), and again multiple serotypes were represented. These data indicate the presence of multiple sources of Salmonella infection in the DCC, posing a complex situation for infection control.