title: Human Schistosoma haematobium antifecundity immunity is dependent on transmission intensity and associated with immunoglobulin G1 to worm-derived antigens.
abstract: BACKGROUND
  Immunity that reduces worm fecundity and, in turn, reduces morbidity is proposed for Schistosoma haematobium, a parasite of major public health importance. Mathematical models of epidemiological trends suggest that antifecundity immunity is dependent on antibody responses to adult-worm-derived antigen.
  
  
  METHODS
  For a Malian cohort (age, 5-29 years) residing in high-transmission fishing villages or a moderate-transmission village, worm fecundity was assessed using the ratio of urinary egg excretion to levels of circulating anodic antigen, a Schistosoma-specific antigen that is steadily secreted by adult worms. Fecundity was modeled against host age, infection transmission intensity, and antibody responses specific to soluble worm antigen (SWA), tegument allergen-like 1, and 28-kDa glutathione-S-transferase.
  
  
  RESULTS
  Worm fecundity declined steadily until a host age of 11 years. Among children, host age and transmission were negatively associated with worm fecundity. A significant interaction term between host age and transmission indicates that antifecundity immunity develops earlier in high-transmission areas. SWA immunoglobulin G1 (IgG1) levels explained the effect of transmission on antifecundity immunity.
  
  
  CONCLUSIONS
  Antifecundity immunity, which is likely to be protective against severe morbidity, develops rapidly during childhood. Antifecundity immunity is associated with SWA-IgG1, with higher infection transmission increasing this response at an earlier age, leading to earlier development of antifecundity immunity.
authors.affiliation: Department of Pathology, University of Cambridge, United Kingdom.
authors.forename: Shona
authors.initials: S
authors.lastname: Wilson
authors.affiliation: Department of Pathology, University of Cambridge, United Kingdom.
authors.forename: Frances M
authors.initials: FM
authors.lastname: Jones
authors.affiliation: Department of Parasitology.
authors.forename: Govert J
authors.initials: GJ
authors.lastname: van Dam
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, The Netherlands.
authors.forename: Paul L A M
authors.initials: PL
authors.lastname: Corstjens
authors.affiliation: CIIL, Inserm U1019, Pasteur Institute, Lille, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Riveau
authors.affiliation: Department of Pathology, University of Cambridge, United Kingdom.
authors.forename: Colin M
authors.initials: CM
authors.lastname: Fitzsimmons
authors.affiliation: Institut National de Recherche en Santé Publique, Bamako, Mali.
authors.forename: Moussa
authors.initials: M
authors.lastname: Sacko
authors.affiliation: Centre for Health Research and Development, Faculty of Life Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: Birgitte J
authors.initials: BJ
authors.lastname: Vennervald
authors.affiliation: Department of Pathology, University of Cambridge, United Kingdom.
authors.forename: David W
authors.initials: DW
authors.lastname: Dunne
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood*; D000947:Antigens, Helminth / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005298:Fertility; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008302:Mali; D008962:Models, Theoretical; D012548:Schistosoma haematobium / Q000276:immunology* / Q000502:physiology; D012553:Schistosomiasis haematobia / Q000276:immunology* / Q000469:parasitology*; D055815:Young Adult
chemical_list: D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D007074:Immunoglobulin G
keywords: Schistosoma haematobium; fecundity; human; immunity; transmission