title: Community cohort study of Cryptosporidium parvum infections: sex-differential incidences associated with BCG and diphtheria-tetanus-pertussis vaccinations.
abstract: OBJECTIVE
  Community studies in West Africa have suggested that routine vaccinations may have sex-differential non-targeted effects, the female-male mortality ratios being increased after receiving diphtheria-tetanus-pertussis (DTP) vaccination and reduced after administration of BCG or measles vaccine (MV). Using an existing data set, we examined whether vaccinations were associated with gender-differential incidences of Cryptosporidium parvum infection.
  
  
  METHODS
  Two hundred children had been recruited shortly after birth and followed until 2 years of age or until follow-up was interrupted by a war. We performed weekly morbidity interviews and collected stool specimens, irrespective of whether the children had diarrhoea. Vaccination status for each child was classified according to the most recent vaccination with BCG, DTP, or MV.
  
  
  RESULTS
  The female-male incidence rate ratio (IRR) for Cryptosporidium infection among children who had received BCG as their last vaccine was 0.0 (95% CI: 0-3.49). However, among those who had received DTP as their last vaccine, the female-male IRR was 6.25 (2.06-18.9) for Cryptosporidium infection and 3.60 (0.91-14.2) for Cryptosporidium-associated diarrhoea. The female-male IRRs for Cryptosporidium infection differed significantly among BCG and DTP recipients (p=0.01). Among children who had received measles as their last routine vaccine, the female-male IRR was 1.57 (0.60-4.11) for Cryptosporidium infection and 0.98 (0.28-3.52) for Cryptosporidium-associated diarrhoea. The female-male IRRs for Cryptosporidium infection differed among DTP and MV recipients (p=0.02). For girls, early DTP vaccination compared with late or no DTP vaccination was associated with increased incidence rate of Cryptosporidium infection (IRR=4.23 (1.04-17.2)). For girls, the incidence rate decreased when they received MV.
  
  
  CONCLUSIONS
  Routine immunisations may affect morbidity for non-targeted infections. As in studies of infant mortality, BCG is associated with a low risk for girls relative to boys, whereas DTP is associated with a high female-male IRR of C. parvum infection.
authors.affiliation: Bandim Health Project, Danish Epidemiology Science Centre, Statens Serum Institut, Apartado 861, Bissau, Guinea-Bissau, Denmark.
authors.forename: Palle
authors.initials: P
authors.lastname: Valentiner-Branth
authors.forename: Michael
authors.initials: M
authors.lastname: Perch
authors.forename: Jens
authors.initials: J
authors.lastname: Nielsen
authors.forename: Hans
authors.initials: H
authors.lastname: Steinsland
authors.forename: May-Lill
authors.initials: ML
authors.lastname: Garly
authors.forename: Thea K
authors.initials: TK
authors.lastname: Fischer
authors.forename: Halvor
authors.initials: H
authors.lastname: Sommerfelt
authors.forename: Kåre
authors.initials: K
authors.lastname: Mølbak
authors.forename: Peter
authors.initials: P
authors.lastname: Aaby
mesh_terms: D000818:Animals; D001500:BCG Vaccine / Q000276:immunology*; D015331:Cohort Studies; D003457:Cryptosporidiosis / Q000453:epidemiology*; D016785:Cryptosporidium parvum; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000276:immunology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012727:Sex Characteristics; D014611:Vaccination
chemical_list: D001500:BCG Vaccine; D015721:Diphtheria-Tetanus-Pertussis Vaccine