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Open Access Research

IgG responses to the gSG6-P1 salivary peptide for evaluating human exposure to Anopheles bites in urban areas of Dakar region, Sénégal

Papa M Drame1*, Vanessa Machault234, Abdoulaye Diallo5, Sylvie Cornélie1, Anne Poinsignon1, Richard Lalou6, Mbacké Sembène7, Stéphanie Dos Santos8, Christophe Rogier29, Frédéric Pagès2, Jean-Yves Le Hesran5 and Franck Remoué10

Author Affiliations

1 Unité Mixte de Recherche MIVEGEC (IRD 224-CNRS 5290-UM1), Institut de Recherche pour le Développement, 34394, Montpellier Cedex 8, France

2 Unité Mixte de Recherche 6236 (URMITE), Institut de Recherche Biomédicale des Armées, Allée du Médecin Colonel Jamot, 13262, Marseille Cedex 07, France

3 Observatoire Midi-Pyrénées, Laboratoire d'Aérologie, Centre National de le Recherche Scientifique, Université Paul Sabatier, 31400, Toulouse, France

4 Centre National d'Etudes Spatiales, Service Applications et Valorisation, 31401, Toulouse Cedex 9, France

5 IRD/UMR 216-Mère et Enfant face aux Infections Tropicales, Faculté des Sciences Pharmaceutiques, 4 avenue de l'Observatoire, 75270, Paris Cedex 06, France

6 Unité Mixte de Recherche 151, Institut de Recherche pour le Développement, Université de Provence, 13331, Marseille Cedex 03, France

7 Département de Biologie Animale, Université Cheikh Anta DIOP, Dakar BP-5005, Sénégal

8 Unité Mixte de Recherche 151, Institut de Recherche pour le Développement, Campus International de Recherche UCAD/IRD de Hann, Dakar BP 1386, Sénégal

9 Institut Pasteur de Madagascar, B.P. 1274, Ambatofotsikely, Antananarivo 101, Madagascar

10 Unité Mixte de Recherche MIVEGEC (IRD 224-CNRS 5290-UM1), Institut de Recherche pour le Développement, Centre de Recherche Entomologique de Cotonou (CREC), BP-4414, Cotonou, RP 01, Benin

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Malaria Journal 2012, 11:72  doi:10.1186/1475-2875-11-72

Published: 16 March 2012

Abstract

Background

Urban malaria can be a serious public health problem in Africa. Human-landing catches of mosquitoes, a standard entomological method to assess human exposure to malaria vector bites, can lack sensitivity in areas where exposure is low. A simple and highly sensitive tool could be a complementary indicator for evaluating malaria exposure in such epidemiological contexts. The human antibody response to the specific Anopheles gSG6-P1 salivary peptide have been described as an adequate tool biomarker for a reliable assessment of human exposure level to Anopheles bites. The aim of this study was to use this biomarker to evaluate the human exposure to Anopheles mosquito bites in urban settings of Dakar (Senegal), one of the largest cities in West Africa, where Anopheles biting rates and malaria transmission are supposed to be low.

Methods

One cross-sectional study concerning 1,010 (505 households) children (n = 505) and adults (n = 505) living in 16 districts of downtown Dakar and its suburbs was performed from October to December 2008. The IgG responses to gSG6-P1 peptide have been assessed and compared to entomological data obtained in or near the same district.

Results

Considerable individual variations in anti-gSG6-P1 IgG levels were observed between and within districts. In spite of this individual heterogeneity, the median level of specific IgG and the percentage of immune responders differed significantly between districts. A positive and significant association was observed between the exposure levels to Anopheles gambiae bites, estimated by classical entomological methods, and the median IgG levels or the percentage of immune responders measuring the contact between human populations and Anopheles mosquitoes. Interestingly, immunological parameters seemed to better discriminate the exposure level to Anopheles bites between different exposure groups of districts.

Conclusions

Specific human IgG responses to gSG6-P1 peptide biomarker represent, at the population and individual levels, a credible new alternative tool to assess accurately the heterogeneity of exposure level to Anopheles bites and malaria risk in low urban transmission areas. The development of such biomarker tool would be particularly relevant for mapping and monitoring malaria risk and for measuring the efficiency of vector control strategies in these specific settings.