Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon.
Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon.
BMC Infect Dis. 2023 Oct 28;23(1):738. doi: 10.1186/s12879-023-08698-8.
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.
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.
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).
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.
代谢抗药性对疟疾传播的影响仍未得到充分描述，尤其是在应用昆虫学参数方面。缺乏抗药性标记物一直是阻止对这种影响进行稳健评估的限制因素之一。为此，本研究旨在调查 L119F-Gste2 代谢基因如何影响蚊子传播疟原虫倾向的昆虫学参数。
在喀麦隆的 Mibellon 和 Elende 两个不同的生态气候环境中进行了纵向研究，使用人体着陆捕获（HLC）、疾病控制中心灯阱（CDC-LT）和除虫菊酯喷雾捕获（PSC）技术收集蚊子。通过 TaqMan 和巢式 PCR 检测疟原虫孢子体寄生虫，通过 ELISA 检测血液来源。使用等位基因特异性 PCR（AS-PCR）方法对 L119F-GSTe2 标记物进行基因分型，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（例如昆虫接种率（EIR）），确定与疟疾传播的关系。
在两个地点的昆虫学调查中，An. funestus s.l 是主要的疟疾传播媒介（在 Elende 和 Mibellon 分别为 86.6%和 96.4%），其次是 An. gambiae s.l（分别为 7.5%和 2.4%）。在两个采集地点，孢子体感染率都非常高（在 Elende 和 Mibellon 分别为 8.7%和 11%）。An. funestus s.s 表现出非常高的昆虫接种率（EIR）（66 个 ib/h/月和 792 个 ib/h/年），并负责两个地点发生的所有疟疾传播事件的 98.6%。两个地点的人类血液指数也很高（HBI=94%）。与易感的 L/L119（SS）相比，携带 119 F/F（RR）和 L119F（RS）基因型的 An. funestus s.s 蚊子具有更高的传播强度（IRR=2.2，95%CI（1.1-5.2），p=0.03；IRR=2.5，95%CI（1.2-5.8），p=0.01）。
本研究强调了 An. funestus s.s 在喀麦隆疟疾传播中的主要作用，并因 GSTe2 代谢抗性而加剧。
