title: Serological Evidence of Contrasted Exposure to Arboviral Infections between Islands of the Union of Comoros (Indian Ocean).
abstract: A cross sectional serological survey of arboviral infections in humans was conducted on the three islands of the Union of Comoros, Indian Ocean, in order to test a previously suggested contrasted exposure of the three neighboring islands to arthropod-borne epidemics. Four hundred human sera were collected on Ngazidja (Grande Comore), Mwali (Mohéli) and Ndzouani (Anjouan), and were tested by ELISA for IgM and/or IgG antibodies to Dengue (DENV), Chikungunya (CHIKV), Rift Valley fever (RVFV), West Nile (WNV), Tick borne encephalitis (TBEV) and Yellow fever (YFV) viruses and for neutralizing antibodies to DENV serotypes 1-4. Very few sera were positive for IgM antibodies to the tested viruses indicating that the sero-survey was performed during an inter epidemic phase for the investigated arbovirus infections, except for RVF which showed evidence of recent infections on all three islands. IgG reactivity with at least one arbovirus was observed in almost 85% of tested sera, with seropositivity rates increasing with age, indicative of an intense and long lasting exposure of the Comorian population to arboviral risk. Interestingly, the positivity rates for IgG antibodies to DENV and CHIKV were significantly higher on Ngazidja, confirming the previously suggested prominent exposure of this island to these arboviruses, while serological traces of WNV infection were detected most frequently on Mwali suggesting some transmission specificities associated with this island only. The study provides the first evidence for circulation of RVFV in human populations from the Union of Comoros and further suggests that the virus is currently circulating on the three islands in an inconspicuous manner. This study supports contrasted exposure of the islands of the Comoros archipelago to arboviral infections. The observation is discussed in terms of ecological factors that may affect the abundance and distribution of vector populations on the three islands as well as concurring anthropogenic factors that may impact arbovirus transmission in this diverse island ecosystem.
authors.affiliation: Centre de Recherche et de Veille sur les Maladies Emergentes dans l'Océan Indien, (CRVOI) Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.|Unité Mixte de Recherche «Processus Infectieux en Milieu Insulaire Tropical» (UMR PIMIT), INSERM 1187 CNRS 9192 IRD 249 Université de La Réunion, Plateforme de Recherche CYROI, Sainte Clotilde, La Réunion, France.
authors.forename: Koussay
authors.initials: K
authors.lastname: Dellagi
authors.affiliation: Aix Marseille Université, IRD, EHESP French School of Public Health, EPV UMR_D 190 "Emergence des Pathologies Virales", Marseille, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Salez
authors.affiliation: French National Reference Centre for Arbovirus, IRBA, Marseille, France.
authors.forename: Marianne
authors.initials: M
authors.lastname: Maquart
authors.affiliation: Cellule Interrégionale d'Épidémiologie Océan Indien (Cire OI), Institut de Veille Sanitaire, Saint Denis, La Réunion, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Larrieu
authors.affiliation: Programme National de Lutte contre le Paludisme, Moroni, Union of the Comoros.
authors.forename: Amina
authors.initials: A
authors.lastname: Yssouf
authors.affiliation: Programme National de Lutte contre le Paludisme, Moroni, Union of the Comoros.
authors.forename: Rahamatou
authors.initials: R
authors.lastname: Silaï
authors.affiliation: French National Reference Centre for Arbovirus, IRBA, Marseille, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Leparc-Goffart
authors.affiliation: Centre de Recherche et de Veille sur les Maladies Emergentes dans l'Océan Indien, (CRVOI) Plateforme de Recherche CYROI, Sainte Clotilde, Reunion Island, France.|Unité Mixte de Recherche «Processus Infectieux en Milieu Insulaire Tropical» (UMR PIMIT), INSERM 1187 CNRS 9192 IRD 249 Université de La Réunion, Plateforme de Recherche CYROI, Sainte Clotilde, La Réunion, France.
authors.forename: Pablo
authors.initials: P
authors.lastname: Tortosa
authors.affiliation: Aix Marseille Université, IRD, EHESP French School of Public Health, EPV UMR_D 190 "Emergence des Pathologies Virales", Marseille, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: de Lamballerie
mesh_terms: D000293:Adolescent; D000328:Adult; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D001102:Arbovirus Infections / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D001103:Arboviruses / Q000276:immunology; D065632:Chikungunya Fever / Q000453:epidemiology / Q000276:immunology / Q000635:transmission / Q000821:virology; D017507:Comoros / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003715:Dengue / Q000453:epidemiology / Q000276:immunology / Q000635:transmission / Q000821:virology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008875:Middle Aged; D000072138:Mosquito Vectors / Q000821:virology; D012295:Rift Valley Fever / Q000453:epidemiology / Q000276:immunology / Q000635:transmission / Q000821:virology; D016036:Seroepidemiologic Studies; D065288:Serogroup; D015004:Yellow Fever / Q000453:epidemiology / Q000276:immunology / Q000635:transmission / Q000821:virology; D055815:Young Adult
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M