title: Seroprevalence of pertussis in Senegal: a prospective study.
abstract: BACKGROUND
  Pertussis, also known as whooping cough, is a vaccine-preventable respiratory disease caused by Bordetella pertussis infection, against which Senegalese children are immunized with the diphtheria-tetanus-whole cell pertussis vaccine (DTwP). Seroepidemiology of pertussis has been widely described in industrialized countries, but rare are the studies referring to it in developing countries.
  
  
  METHODS
  We conducted a longitudinal survey in Northern Senegal to investigate the epidemiology of B. pertussis by evaluating the IgG antibody (Ab) response against pertussis toxin (PT). A cohort of 410 children aged 1 to 9 from five villages in the Middle Senegal River Valley were followed-up for 18 months. During that period, five visits were made to assess the immunological status of the children.
  
  
  RESULTS
  PT-specific IgG responses were significantly different according to age. Until the age of 3, there was a decrease in the Ab response, which then increased in the older groups. Assessment of IgG antibodies to PT (IgG-PT) suggested evidence of recent exposures to the pathogen. Surprisingly, in one of the five villages the average Ab response to PT was very low at all ages during the first 6 months of the study. At the third visit, IgG-PT concentrations peaked to very high levels, to slightly decline at the end of the survey. This indicates an outbreak of B. pertussis, whereas in the other villages a pertussis endemic profile could be observed.
  
  
  CONCLUSIONS
  Pertussis is endemic in Northern Senegal despite the introduction of vaccination. The circulation of the bacteria seems to differ between geographic locations and over time. A more complete understanding of the epidemiology of pertussis and its environmental determinants could provide information to adapt vaccination programs.
authors.affiliation: Centre for Infection and Immunity of Lille - U1019 Inserm, UMR8204 CNRS, Institut Pasteur de Lille, Lille, France. lobna.gaayeb@gmail.com
authors.forename: Lobna
authors.initials: L
authors.lastname: Gaayeb
authors.forename: Jean Biram
authors.initials: JB
authors.lastname: Sarr
authors.forename: Mamadou O
authors.initials: MO
authors.lastname: Ndiath
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Hanon
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Debrie
authors.forename: Modou
authors.initials: M
authors.lastname: Seck
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Schacht
authors.forename: Franck
authors.initials: F
authors.lastname: Remoué
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Hermann
authors.forename: Gilles
authors.initials: G
authors.lastname: Riveau
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D001886:Bordetella pertussis / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D003906:Developing Countries; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage / Q000276:immunology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007223:Infant; D008297:Male; D037342:Pertussis Toxin / Q000276:immunology*; D011054:Poliovirus Vaccine, Inactivated / Q000008:administration & dosage / Q000276:immunology*; D011446:Prospective Studies; D012675:Senegal / Q000453:epidemiology; D016036:Seroepidemiologic Studies; D013997:Time Factors; D017778:Vaccines, Combined / Q000008:administration & dosage / Q000276:immunology; D014917:Whooping Cough / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control
chemical_list: D000907:Antibodies, Bacterial; C051021:DTPP vaccine; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D007074:Immunoglobulin G; D011054:Poliovirus Vaccine, Inactivated; D017778:Vaccines, Combined; D037342:Pertussis Toxin