背景:通过应用昆虫学参数,对杀虫剂的代谢抗性对疟疾传播的影响仍然缺乏明显的表征。缺乏抗性标记是阻碍对这种影响进行稳健评估的限制因素之一。为此,本研究试图调查L119F-Gste2代谢基因如何影响昆虫参数,这些参数支持蚊子传播疟原虫的倾向。
方法:在Mibellon和Elende进行了纵向研究,喀麦隆的两种不同的生态气候环境和蚊子是使用人类着陆捕获(HLC)收集的,疾病控制中心光阱(CDC-LT)和除虫菊喷雾捕获(PSC)技术。通过TaqMan和巢式PCR检测疟原虫子孢子寄生虫,和通过ELISA的血粉来源。使用等位基因特异性PCR(AS-PCR)方法对L119F-GSTe2标记进行基因分型,并通过比较具有不同L119F-GSTe2基因型的个体之间的关键传播参数如昆虫接种率(EIR),建立与疟疾传播的关联。
结果:An.funestuss.l是两个地点昆虫学调查期间收集的主要疟疾媒介(Elende和Mibellon分别为86.6%和96.4%,分别),其次是An。冈比亚s.l(7.5%和2.4%,分别)。两个采集点的子孢子感染率都很高(Elende和Mibellon分别为8.7%和11%,分别)。A.funestuss.s表现出很高的昆虫学接种率(EIR)(66ib/h/月和792ib/h/年),占两个地点发生的所有疟疾传播事件的98.6%。人类血液指数在这两个地方也很高(HBI=94%)。A.具有119F/F(RR)和L119F(RS)基因型的funestuss.s.蚊子的传播强度明显高于其易感的L/L119(SS)对应物(IRR=2.2,95CI(1.1-5.2),p=0.03;IRR=2.5,95%CI(1.2-5.8),分别为p=0.01)。
结论:这项研究强调了An的主要作用。funestuss.s在喀麦隆的疟疾传播中起作用,并且由于基于GSTe2的代谢抗性而加剧。
BACKGROUND: The impact of metabolic resistance to insecticides on malaria transmission remains poorly characterised notably through application of entomological parameters. The lack of resistance markers has been one of the limiting factors preventing a robust assessment of such impact. To this end, the present study sought to investigate how the L119F-Gste2 metabolic gene influences entomological parameters underpinning mosquitos\' propensity to transmit Plasmodium spp.
METHODS: Longitudinal studies were carried out in Mibellon and Elende, two different eco-climatic settings in Cameroon and mosquitoes were collected using Human Landing Catch (HLC), Centre for Disease Control Light Trap (CDC-LT) and Pyrethrum Spray Catch (PSC) technics. Plasmodium sporozoite parasites were detected by TaqMan and Nested PCR, and blood meal origin by ELISA. The allele-specific PCR (AS-PCR) method was used to genotype the L119F-GSTe2 marker and association with malaria transmission was established by comparing key transmission parameters such as the Entomological Inoculation Rate (EIR) between individuals with different L119F-GSTe2 genotypes.
RESULTS: An. funestus s.l was the predominant malaria vector collected during the entomological survey in both sites (86.6% and 96.4% in Elende and Mibellon, respectively) followed by An. gambiae s.l (7.5% and 2.4%, respectively). Sporozoite infection rates were very high in both collection sites (8.7% and 11% in Elende and Mibellon, respectively). An. funestus s.s exhibited a very high entomological inoculation rate (EIR) (66 ib/h/month and 792 ib/h/year) and was responsible for 98.6% of all malaria transmission events occurring in both sites. The Human Blood Index was also high in both locations (HBI = 94%). An. funestus s.s. mosquitoes with both 119 F/F (RR) and L119F (RS) genotypes had a significantly higher transmission intensity than their susceptible L/L119 (SS) counterparts (IRR = 2.2, 95%CI (1.1-5.2), p = 0.03; IRR = 2.5, 95% CI (1.2-5.8), p = 0.01 respectively).
CONCLUSIONS: This study highlights the major role that An. funestus s.s plays in malaria transmission in Cameroon with an aggravation from GSTe2-based metabolic resistance.