title: Plasmodium falciparum infection during dry season: IgG responses to Anopheles gambiae salivary gSG6-P1 peptide as sensitive biomarker for malaria risk in Northern Senegal.
abstract: BACKGROUND
  The Northern part of Senegal is characterized by a low and seasonal transmission of malaria. However, some Plasmodium falciparum infections and malaria clinical cases are reported during the dry season. This study aims to assess the relationship between IgG antibody (Ab) responses to gSG6-P1 mosquito salivary peptide and the prevalence of P. falciparum infection in children during the dry season in the Senegal River Valley. The positive association of the Ab response to gSG6-P1, as biomarker of human exposure to Anopheles vector bite, and P. falciparum infectious status (uninfected, infected-asymptomatic or infected-symptomatic) will allow considering this biomarker as a potential indicator of P. falciparum infection risk during the dry season.
  
  
  METHODS
  Microscopic examination of thick blood smears was performed in 371 and 310 children at the start (January) and at the end (June) of the dry season, respectively, in order to assess the prevalence of P. falciparum infection. Collected sera were used to evaluate IgG response to gSG6-P1 by ELISA. Association between parasitological and clinical data (infected-asymptomatic or infected-symptomatic) and the anti-gSG6-P1 IgG levels were evaluated during this period.
  
  
  RESULTS
  The prevalence of P. falciparum infection was very low to moderate according to the studied period and was higher in January (23.5%) compared to June (3.5%). Specific IgG response was also different between uninfected children and asymptomatic carriers of the parasite. Children with P. falciparum infection in the dry season showed higher IgG Ab levels to gSG6-P1 than uninfected children.
  
  
  CONCLUSIONS
  The results strengthen the hypothesis that malaria transmission is maintained during the dry season in an area of low and seasonal transmission. The measurement of IgG responses to gSG6-P1 salivary peptide could be a pertinent indicator of human malaria reservoir or infection risk in this particular epidemiological context. This promising immunological marker could be useful for the evaluation of the risk of P. falciparum exposure observed during dry season and, by consequences, could be used for the survey of potential pre-elimination situation.
authors.affiliation: Centre de Recherche Biomédicale Espoir Pour La Santé, 269 Route de la corniche, Sor, BP: 226, Saint-Louis, Sénégal. andre.sagna@espoir-sante.org.
authors.forename: André B
authors.initials: AB
authors.lastname: Sagna
authors.forename: Lobna
authors.initials: L
authors.lastname: Gaayeb
authors.forename: Jean B
authors.initials: JB
authors.lastname: Sarr
authors.forename: Simon
authors.initials: S
authors.lastname: Senghor
authors.forename: Anne
authors.initials: A
authors.lastname: Poinsignon
authors.forename: Samy
authors.initials: S
authors.lastname: Boutouaba-Combe
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Schacht
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Hermann
authors.forename: Ngor
authors.initials: N
authors.lastname: Faye
authors.forename: Franck
authors.initials: F
authors.lastname: Remoue
authors.forename: Gilles
authors.initials: G
authors.lastname: Riveau
mesh_terms: D000818:Animals; D015415:Biomarkers; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D019476:Insect Proteins / Q000276:immunology*; D008137:Longitudinal Studies; D016778:Malaria, Falciparum / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D010963:Plasmodium falciparum / Q000276:immunology* / Q000302:isolation & purification; D018570:Risk Assessment; D012471:Salivary Proteins and Peptides / Q000276:immunology*; D012621:Seasons; D012675:Senegal / Q000453:epidemiology; D016036:Seroepidemiologic Studies
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G; D019476:Insect Proteins; D012471:Salivary Proteins and Peptides