title: Seasonal and sex-specific variations in haematological parameters in 4 to 5.5-month-old infants in Guinea-Bissau, West Africa.
abstract: This study investigated seasonal and sex-specific variations in the haematological parameters and established reference ranges for these parameters in healthy 4 to 5.5-month-old infants in Guinea-Bissau.
  
  
  
  Within a randomised trial of early measles vaccination, over a period of 13 months blood samples were collected from infants aged 4 to 5.5 months. Haematological parameters were determined by an automated cell counter and compared in linear regression models providing geometric mean ratios (GMR).
  
  
  
  Blood samples from 501 infants (n=248 boys, 49.5%) were obtained, and 285 (56.9%) were collected in the rainy season. Median age was 4.7 months (range 3.7 to 7.2 months). Eosinophil and platelet counts were lower in the dry season (December to May) than in the rainy season (GMR 0.79 [95% CI 0.68-0.92]) and 0.93 [0.87-1.00], respectively). The calculated reference ranges were wider and generally higher than those from a US population of comparable age, but neutrophil levels were notably lower in Guinea-Bissau.
  
  
  
  The study indicated that eosinophil and platelet counts of infants were subject to seasonal variations. The reference ranges for haematological values were comparable to other African populations and corroborated that neutropenia regularly occurs in African infants.
authors.affiliation: Bandim Health Project, Indepth Network, codex 1004, Bissau, Guinea-Bissau.|Department of Infectious Diseases, Hvidovre Hospital, DK-2650 Copenhagen, Denmark.
authors.forename: Ole
authors.initials: O
authors.lastname: Bæk
authors.affiliation: Bandim Health Project, Indepth Network, codex 1004, Bissau, Guinea-Bissau.|Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, DK-2300 Copenhagen, Denmark.
authors.forename: Kristoffer Jarlov
authors.initials: KJ
authors.lastname: Jensen
authors.affiliation: Bandim Health Project, Indepth Network, codex 1004, Bissau, Guinea-Bissau.|Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, DK-2300 Copenhagen, Denmark.
authors.forename: Andreas
authors.initials: A
authors.lastname: Andersen
authors.affiliation: Bandim Health Project, Indepth Network, codex 1004, Bissau, Guinea-Bissau.
authors.forename: Carlito
authors.initials: C
authors.lastname: Balé
authors.affiliation: Bandim Health Project, Indepth Network, codex 1004, Bissau, Guinea-Bissau.
authors.forename: Cesario
authors.initials: C
authors.lastname: Martins
authors.affiliation: Bandim Health Project, Indepth Network, codex 1004, Bissau, Guinea-Bissau.|Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, DK-2300 Copenhagen, Denmark.
authors.forename: Sofie
authors.initials: S
authors.lastname: Biering-Sørensen
authors.affiliation: Department of Paediatrics and Adolescent Medicine, Rigshospitalet, DK-2100 Copenhagen, Denmark.
authors.forename: Anja
authors.initials: A
authors.lastname: Poulsen
authors.affiliation: Bandim Health Project, Indepth Network, codex 1004, Bissau, Guinea-Bissau.|Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, DK-2300 Copenhagen, Denmark.|OPEN, University of Southern Denmark/Odense University Hospital, DK-4000 Odense, Denmark.
authors.forename: Christine Stabell
authors.initials: CS
authors.lastname: Benn
mesh_terms: D001772:Blood Cell Count; D001792:Blood Platelets; D004804:Eosinophils; D005260:Female; D006169:Guinea-Bissau; D006405:Hematology; D006801:Humans; D007223:Infant; D008297:Male; D010976:Platelet Count; D011891:Rain; D012016:Reference Values; D012621:Seasons; D014611:Vaccination; D014887:Weather
keywords: Africa; Differential count; Haematology; Infant; Season; Sex difference