High level of resistance in the mosquito Anopheles gambiae to pyrethroid insecticides and reduced susceptibility to bendiocarb in north-western Tanzania

Malaria Journal

Research

Alexandra Wright¹  Natacha Protopopoff¹  Mark Rowland¹  Philippa A West²  Robert Kaaya³  Johnson Matowo³  Reginald Kavishe³  Franklin W Mosha³  Immo Kleinschmidt⁴  Robert Malima⁵  William Kisinza⁵ 

[1] Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK;Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, Keppel Street, London, UK;Kilimanjaro Christian Medical College, Tumaini University, Moshi, Tanzania;MRC Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, Keppel Street, London, UK;National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania;

关键词: Insecticide resistance;    Knock down mutation;    Anopheles arabiensis;    Anopheles gambiae;    Tanzania;    Pyrethroid;    Bendiocarb;    Indoor residual spraying;    Long-lasting insecticidal net;   

DOI  :  10.1186/1475-2875-12-149

 received in 2013-02-25, accepted in 2013-04-19,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundTo control malaria in Tanzania, two primary vector control interventions are being scaled up: long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS). The main threat to effective malaria control is the selection of insecticide resistance. While resistance to pyrethroids, the primary insecticide used for LLINs and IRS, has been reported among mosquito vectors in only a few sites in Tanzania, neighbouring East African countries are recording increasing levels of resistance. To monitor the rapidly evolving situation, the resistance status of the malaria vector Anopheles gambiae s.l to different insecticides and the prevalence of the kdr resistance allele involved in pyrethroid resistance were investigated in north-western Tanzania, an area that has been subject to several rounds of pyrethroid IRS since 2006.MethodsHousehold collections of anopheline mosquitoes were exposed to diagnostic dosages of pyrethroid, DDT, and bendiocarb using WHO resistance test kits. The relative proportions of An. gambiae s.s and Anopheles arabiensis were also investigated among mosquitoes sampled using indoor CDC light traps. Anophelines were identified to species and the kdr mutation was detected using real time PCR TaqMan assays.ResultsFrom the light trap collections 80% of An. gambiae s.l were identified as An. gambiae s.s and 20% as An. arabiensis. There was cross-resistance between pyrethroids and DDT with mortality no higher than 40% reported in any of the resistance tests. The kdr-eastern variant was present in homozygous form in 97% of An. gambiae s.s but was absent in An. arabiensis. Anopheles gambiae s.s showed reduced susceptibility to the carbamate insecticide, bendiocarb, the proportion surviving WHO tests ranging from 0% to 30% depending on season and location.ConclusionAnopheles gambiae s.s has developed phenotypic resistance to pyrethroids and DDT and kdr frequency has almost reached fixation. Unlike in coastal Tanzania, where the ratio of An. gambiae s.s to An. arabiensis has decreased in response to vector control, An. gambiae s.s persists at high frequency in north-western Tanzania, probably due to selection of pyrethroid resistance, and this trend is likely to arise in other areas as resistance spreads or is subject to local selection from IRS or LLINs.

【 授权许可】

CC BY   
© Protopopoff et al.; licensee BioMed Central Ltd. 2013