Spatio-seasonal distribution of Anopheles gambiae sensu lato and dynamics of the Voltage gate sodium channel knock down resistance mutation (Vgsc1014F) in the city of Lomé, Togo

Abstract

Poor planned urbanization sustains the presence of malaria vectors in some urban areas. Here, we provide information on the spatial and seasonal distribution of Anopheles gambiae sensu lato and the dynamics of kdr mutation in Lomé, the capital city of Togo. Anopheles Larvae were collected in Lomé from January to December 2005, to assess their frequency and abundance. Susceptibility tests were performed from 2006 to 2009 on adults of Anopheles gambiae s.l. that emerged from the larvae collected at Akodesséwa following the WHO standard protocol, using DDT, deltamethrin, and permethrin. A molecular assessment of pyrethroid knockdown resistance (Vgsc-1014F kdr) was also conducted. In 2005, a total of 2,397 Anopheles gambiae s.l. larvae were collected. Out of 124 adults identified by PCR, 92.7% were An. coluzzii/An. gambiae and 13.2% were An. arabiensis. Anopheles coluzzii was more frequent throughout the year regardless the season whereas An. gambiae and An. arabiensis were more specific to the rainy seasons. A decrease of susceptibility was observed in An. gambiae s.l. during the 3 rounds. The Vgsc-1014F kdr frequency varied from 7.5% to 8.7%. This situation could affect the success of the integrated distribution campaign to provide individuals with ITNs and LLINs in Togo. 

Keywords: Breeding sites, Anopheles gambiae s.l., insecticide resistance, dynamics, Vgsc-1014F kdr mutation.