title: Vitamin A supplementation has divergent effects on norovirus infections and clinical symptoms among Mexican children.
abstract: BACKGROUND
  The effect of vitamin A supplementation on viral gastrointestinal infections among young children living in developing countries remains unclear.
  
  
  METHODS
  The effect of vitamin A supplementation on norovirus (NoV) infection among 127 Mexican children 5-15 months of age was studied in a randomized, placebo-controlled trial during June-August 1998. Stool samples collected every 2 weeks and after diarrheal episodes were screened for NoV and characterized at the genogroup level (GI and GII).
  
  
  RESULTS
  Of the stool samples collected, 29.9% were positive for NoV, and NoV GI and NoV GII were found in 55.4% and 46.4% of the positive samples, respectively. Vitamin A supplementation reduced the prevalence of NoV GII infections (rate ratio [RR], 0.60 [95% confidence interval {CI}, 0.20-0.82]), increased the length of both NoV GI and GII shedding, and decreased the prevalence of NoV-associated diarrhea (RR, 0.51 [95% CI, 0.26-0.97]).
  
  
  CONCLUSIONS
  These findings suggest that NoV is an important cause of pediatric diarrhea in this study population and that vitamin A supplementation has divergent effects on specific outcomes of NoV infection.
authors.affiliation: Department of Nutrition, Harvard School of Public Health, Boston, MA, USA. k.long@uq.edu.au
authors.forename: Kurt Z
authors.initials: KZ
authors.lastname: Long
authors.forename: Coralith
authors.initials: C
authors.lastname: Garcia
authors.forename: Jose I
authors.initials: JI
authors.lastname: Santos
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Rosado
authors.forename: Ellen
authors.initials: E
authors.lastname: Hertzmark
authors.forename: Herbert L
authors.initials: HL
authors.lastname: Dupont
authors.forename: Gwangpyo
authors.initials: G
authors.lastname: Ko
mesh_terms: D017250:Caliciviridae Infections / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology; D005243:Feces / Q000821:virology; D005260:Female; D005759:Gastroenteritis / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology / Q000821:virology; D006801:Humans; D007223:Infant; D008297:Male; D008800:Mexico / Q000453:epidemiology; D029322:Norovirus / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D015995:Prevalence; D016896:Treatment Outcome; D014801:Vitamin A / Q000008:administration & dosage / Q000627:therapeutic use; D014815:Vitamins / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D014815:Vitamins; D014801:Vitamin A