title: Asymptomatic salmonellosis among children in day-care centers in Mérida, Yucatan, Mexico.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  These data indicate the presence of multiple sources of Salmonella infection in the DCC, posing a complex situation for infection control.
authors.affiliation: Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA 70112, USA. oberhel@tulane.edu
authors.forename: R A
authors.initials: RA
authors.lastname: Oberhelman
authors.forename: J
authors.initials: J
authors.lastname: Flores-Abuxapqui
authors.forename: G
authors.initials: G
authors.lastname: Suarez-Hoil
authors.forename: M
authors.initials: M
authors.lastname: Puc-Franco
authors.forename: M
authors.initials: M
authors.lastname: Heredia-Navarrete
authors.forename: M
authors.initials: M
authors.lastname: Vivas-Rosel
authors.forename: R
authors.initials: R
authors.lastname: Mera
authors.forename: L
authors.initials: L
authors.lastname: Gutierrez-Cogco
mesh_terms: D002656:Child Day Care Centers; D002675:Child, Preschool; D003967:Diarrhea / Q000453:epidemiology* / Q000382:microbiology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008800:Mexico / Q000453:epidemiology; D012475:Salmonella / Q000145:classification* / Q000302:isolation & purification*; D012480:Salmonella Infections / Q000453:epidemiology* / Q000382:microbiology