title: Natural rotavirus infection is not associated to intussusception in Mexican children.
abstract: OBJECTIVE
  To determine whether natural rotavirus infection or infection by another enteropathogen is associated to intussusception (IS); and to describe the seasonality of IS compared with severe diarrhea (SD) and rotavirus SD in Mexican children.
  
  
  METHODS
  A prospective, observational, multicenter and case-control study was conducted in Mexico City from December 1999 to February 2001. Cases were children younger than 1 year old hospitalized for IS; diagnosis was made by clinical features, radiologic and/or surgery findings. Controls were children younger than 1 year old hospitalized for another disease than a gastrointestinal illness (NGI). Cases and controls were paired by age and date of admission (+/-3 months; for both), in a 1:2 ratio. A surveillance of IS cases, SD and rotavirus SD episodes was conducted during the study period. Stool samples collected soon after IS resolution or at admission were tested for rotavirus, adenovirus, astrovirus, bacteria and parasites.
  
  
  RESULTS
  Thirty cases of IS and 60 controls with NGI were studied. Rotavirus was not detected in any case of IS. Adenovirus (17%) was the only enteropathogen detected in IS. Rotavirus (8%), adenovirus (2%), astrovirus (2%) and bacteria (2%) were detected in NGI. Rotavirus infection was not associated with IS (odds ratio, 0; 95% confidence interval, 0-2.9), whereas adenovirus infection was strongly associated as risk factor for IS (odds ratio undefined; P = 0.003), compared with NGI. Seasonal variation in admissions for IS was small, whereas admissions for SD and rotavirus SD showed a marked seasonal increase during fall-winter.
  
  
  CONCLUSIONS
  In Mexican children, rotavirus infection was not associated to IS; whereas a significant association was observed between adenovirus and IS. Also there was no increase in IS cases during the sharply defined fall-winter rotavirus outbreak. Observations from this controlled study suggest that natural rotavirus infection is not a risk factor for IS. This information may have implications for development of a safer and effective rotavirus vaccine.
authors.affiliation: Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico. fraulv@infosel.net.mx
authors.forename: F Raúl
authors.initials: FR
authors.lastname: Velázquez
authors.forename: Guillermina
authors.initials: G
authors.lastname: Luna
authors.forename: Roberto
authors.initials: R
authors.lastname: Cedillo
authors.forename: Javier
authors.initials: J
authors.lastname: Torres
authors.forename: Onofre
authors.initials: O
authors.lastname: Muñoz
mesh_terms: D000257:Adenoviridae Infections / Q000150:complications* / Q000453:epidemiology; D016022:Case-Control Studies; D003967:Diarrhea / Q000453:epidemiology / Q000821:virology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007443:Intussusception / Q000821:virology*; D008800:Mexico / Q000453:epidemiology; D016017:Odds Ratio; D011159:Population Surveillance; D011446:Prospective Studies; D012400:Rotavirus Infections / Q000150:complications* / Q000453:epidemiology; D012621:Seasons