Biomarqueurs immuno-épidémiologiques d’exposition de l’homme aux piqûres des moustiques Aedes et Culex : application à l'évaluation du risque de transmission des arboviroses

Arboviruses, transmitted by the Aedes and Culex mosquitoes, continue to threaten the health and lives of populations in areas where they are endemic and represent risks of emergence in new territories colonised by these vectors. The main objective of our work was i) to assess the level of exposure of populations to the bites of Aedes aegypti and Ae. albopictus and the risk of transmission of the diseases they transmit, in an urban environment in West Africa and in the South of metropolitan France and ii) to evaluate and validate the anti-EGS IgG and anti-recombinant 30 kDa protein responses of Culex quinquefasciatus as a potential biomarker of human exposure to Culex bites. We measured in the sera of exposed individuals, the antibody responses: i) IgG anti-Nterm-34 kDa and IgG anti arbovirus antigens (LUMINEX) in children from Anoumabo, Bromakoté and Petit-Bassam, in Abidjan, ii) IgG and IgM anti-Nterm-34 kDa of Ae. aegypti in Auvergne, Corsica, Occitania and PACA, France, and iii) anti-EGS IgG and recombinant 30 kDa protein in children from Dar-es-Salam, N'Gattakro, Kennedy in Bouaké.In Abidjan, anti-Nterm-34 kDa IgG was significantly different between the study districts with a high level in Bromakoté. Specific IgG was associated with sticky trap data. According to the LUMINEX technique, arboviruses were circulating in the districts, with a majority detection of DENV3. Petit-Bassam was the most affected. All these results showed that exposure to Aedes and thus the risk of transmission varied between neighbourhoods within the same African city.In metropolitan France, specific IgG was higher in the colonised areas than in the uncolonised area. The specific IgG response was higher in Occitania and PACA compared to Corsica. The anti-salivary peptide IgM, indicated a significant difference between the exposed regions. In Occitanie, the median levels of anti-peptide IgG responses in departments 30 and 34 were higher than those in departments 31 and 66. In PACA, a significant difference in the level of specific IgG was detected between departments 04 and 13 and between departments 05 and 13. IgG levels in departments 13 and 83 were higher than in the other departments. Departments colonised between 2010 and 2012 had statically higher anti-peptide IgG levels than non-colonised departments. IgM between individuals in the 4 regions was practically zero. These results indicated the relevance of the salivary anti-peptide IgG biomarker to discriminate the regions and departments most exposed to Ae. albopictus bites and thus to assess the heterogeneity of arbovirosis transmission risks in metropolitan France.For Culex, anti-EGS and anti-30 kDa IgG responses were significantly higher in children living in sites of high Culex quinquefasciatus density. Anti-30 kDa IgG was significantly higher in children not sleeping under insecticide-treated nets compared to those sleeping under them. In addition, a positive correlation was observed between anti-EGS IgG responses and anti-30 kDa IgG Ac in the total population.This study showed that the use of biomarkers of exposure to Aedes bites could be a relevant tool for the assessment of heterogeneity of exposure to arbovirus vectors in the African urban context and between departments of the same region in southern France. Anti-EGS IgG and anti-30 kDa protein responses would represent potential biomarker candidates for Culex bites. However further studies are needed, to validate them as a biomarker of Culex exposure

Topic: Mosquito-borne diseases and control
Subfield: Public Health, Environmental and Occupational Health
Field: Medicine
Domain: Health Sciences