Dabiré K. R. auteur aut IRD Diabaté A. auteur aut IRD Djogbénou Luc auteur aut IRD Ouari A. auteur aut IRD N'Guessan R. auteur aut IRD Ouédraogo J. B. auteur aut IRD Hougard Jean-Marc auteur aut IRD Chandre Fabrice auteur aut IRD Baldet T. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Background: Insecticide resistance of the main malaria vector, Anopheles gambiae, has been reported in south-western Burkina Faso, West Africa. Cross-resistance to DDT and pyrethroids was conferred by alterations at site of action in the sodium channel, the Leu-Phe kdr mutation; resistance to organophosphates and carbamates resulted from a single point mutation in the oxyanion hole of the acetylcholinesterase enzyme designed as ace-1(R). Methods: An entomological survey was carried out during the rainy season of 2005 at Vallee du Kou, a rice growing area in south-western Burkina Faso. At the Vallee du Kou, both insecticide resistance mechanisms have been previously described in the M and S molecular forms of An. gambiae. This survey aimed i) to update the temporal dynamics and the circumsporozoite infection rate of the two molecular forms M and S of An. gambiae ii) to update the frequency of the Leu-Phe kdr mutation within these forms and finally iii) to investigate the occurrence of the ace-1(R) mutation. Mosquitoes collected by indoor residual collection and by human landing catches were counted and morphologically identified. Species and molecular forms of An. gambiae, ace-1(R) and Leu-Phe kdr mutations were determined using PCR techniques. The presence of the circumsporozoite protein of Plasmodium falciparum was determined using ELISA. Results: Anopheles gambiae populations were dominated by the M form. However the S form occurred in relative important proportion towards the end of the rainy season with a maximum peak in October at 51%. Sporozoite rates were similar in both forms. The frequency of the LeuPhe kdr mutation in the S form reached a fixation level while it is still spreading in the M form. Furthermore, the ace-1(R) mutation prevailed predominately in the S form and has just started spreading in the M form. The two mutations occurred concomitantly both in M and S populations. Conclusion: These results showed that the Vallee du Kou, a rice growing area formerly occupied mainly by M susceptible populations, is progressively colonized by S resistant populations living in sympatry with the former. As a result, the distribution pattern of insecticide resistance mutations shows the occurrence of both resistance mechanisms concomitantly in the same populations. The impact of multiple resistance mechanisms in M and S populations of An. gambiae on vector control measures against malaria transmission, such as insecticide-treated nets (ITNs) and indoor residual spraying (IRS), in this area is discussed. specialized 052 7 2008 1475-2875 https://www.documentation.ird.fr/hor/fdi:010044067 10.1186/1475-2875-7-188 1475-2875 [F B010044067] https://www.documentation.ird.fr/hor/fdi:010044067 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers17-09/010044067.pdf IRD - Base Horizon / Pleins textes 2008-12-05 2017-10-03 fdi:010044067 fre