背景:了解持续疟疾传播的感染集群对于确定如何以及在何处针对特定干预措施至关重要。本研究旨在确定密度,通过针对疟疾指数病例,血餐来源和按蚊媒介传播疟疾的风险,他们在Arjo-Didessa的邻近家庭和控制村庄,埃塞俄比亚西南部。
方法:于2019年11月至2021年10月在ArjoDidessa及其附近地区进行了一项昆虫学研究,同时进行了一项反应性病例检测(RCD)研究。埃塞俄比亚西南部。在指示病例家庭及其周围家庭(相邻家庭)的室内和室外收集了按蚊,以及在控制家庭中,使用除虫菊喷雾缓存(PSC)和美国疾病控制和预防中心(CDC)的光陷阱。对成年蚊子进行了形态学鉴定,并通过PCR进行冈比亚按蚊复合体的形态鉴定。通过环子孢子蛋白酶联免疫吸附试验(CSP-ELISA)和基于细胞色素b的血餐PCR检测蚊子疟原虫感染和宿主血餐来源,分别。
结果:在收集的770只按蚊中,A.冈比亚感官拉托(A.冈比亚s.l.)是主要物种,占渔获量的87.1%(n=671/770),其次是按蚊和按蚊,占渔获量的12.6%(n=97/770)和0.26%(n=2/770),分别。从An的子样本中。冈比亚s.l.用PCR分析,A.鉴定了阿拉伯和按蚊。使用CDC光诱捕器,蚊子的总平均密度为每个诱捕器每晚1.26只蚊子。室外蚊虫密度明显高于室内蚊虫密度指数和邻近住户(P=0.0001)。An的人血液指数(HBI)和牛血指数(BBI)。阿拉伯分别为20.8%(n=34/168)和24.0%(n=41/168),分别。按蚊的总疟原虫子孢子感染率(An。阿拉伯和安。coustani复合物)为4.4%(n=34/770)。在捕获的按蚊蚊子中在室内和室外检测到子孢子。在这些CSP阳性物种中,Pv-210,Pv-247和Pf,41.1%(n=14/34)在户外捕获。在指标病例家庭中捕获的子孢子感染蚊子的比例明显更高(5.6%,n=8/141)与对照家庭(1.1%,n=2/181)(P=0.02),和邻近家庭(5.3%,与对照组家庭相比,n=24/448)(P=0.01)。
结论:这项研究的结果表明,疟疾指数病例及其邻近家庭的室外蚊子密度和疟原虫感染率较高。该研究还强调了相对较高的室外蚊子密度,这可能会增加室外疟疾传播的潜在风险,并可能在残留疟疾传播中起作用。因此,加强病媒控制干预措施的实施非常重要,例如有针对性的室内残留喷洒,长效杀虫网和其他辅助媒介控制措施,如幼虫源管理和社区参与方法。此外,在低传输设置中,比如ArjoDidessa甘蔗种植园,为当地社区提供健康教育,加强环境管理和昆虫学监测,通过针对疟疾指数病例及其近邻家庭进行病例发现和管理,可能是控制残留疟疾传播和实现有针对性的消除目标的重要措施。
BACKGROUND: Understanding the clustering of infections for persistent malaria transmission is critical to determining how and where to target specific interventions. This study aimed to determine the density, blood meal sources and malaria transmission risk of anopheline vectors by targeting malaria index cases, their neighboring households and control villages in Arjo-Didessa, southwestern Ethiopia.
METHODS: An entomological study was conducted concurrently with a reactive
case detection (RCD) study from November 2019 to October 2021 in Arjo Didessa and the surrounding vicinity, southwestern Ethiopia. Anopheline mosquitoes were collected indoors and outdoors in index
case households and their surrounding households (neighboring households), as well as in control households, using pyrethrum spray cache (PSC) and U.S. Centers for Disease Control and Prevention (CDC) light traps. Adult mosquitoes were morphologically identified, and speciation in the Anopheles gambiae complex was done by PCR. Mosquito Plasmodium infections and host blood meal sources were detected by circumsporozoite protein enzyme-linked immunosorbent assay (CSP-ELISA) and cytochrome b-based blood meal PCR, respectively.
RESULTS: Among the 770 anopheline mosquitoes collected, An. gambiae sensu lato (A. gambiae s.l.) was the predominant species, accounting for 87.1% (n = 671/770) of the catch, followed by the Anopheles coustani complex and Anopheles pharoensis, which accounted for 12.6% (n = 97/770) and 0.26% (n = 2/770) of the catch, respectively. From the sub-samples of An. gambiae s.l.analyzed with PCR, An. arabiensis and Anopheles amharicus were identified. The overall mean density of mosquitoes was 1.26 mosquitoes per trap per night using the CDC light traps. Outdoor mosquito density was significantly higher than indoor mosquito density in the index and neighboring households (P = 0.0001). The human blood index (HBI) and bovine blood index (BBI) of An. arabiensis were 20.8% (n = 34/168) and 24.0% (n = 41/168), respectively. The overall Plasmodium sporozoite infection rate of anophelines (An. arabiensis and An. coustani complex) was 4.4% (n = 34/770). Sporozoites were detected indoors and outdoors in captured anopheline mosquitoes. Of these CSP-positive species for Pv-210, Pv-247 and Pf, 41.1% (n = 14/34) were captured outdoors. A significantly higher proportion of sporozoite-infected mosquitoes were caught in index
case households (5.6%, n = 8/141) compared to control households (1.1%, n = 2/181) (P = 0.02), and in neighboring households (5.3%, n = 24/448) compared to control households (P = 0.01).
CONCLUSIONS: The findings of this study indicated that malaria index cases and their neighboring households had higher outdoor mosquito densities and Plasmodium infection rates. The study also highlighted a relatively higher outdoor mosquito density, which could increase the potential risk of outdoor malaria transmission and may play a role in residual malaria transmission. Thus, it is important to strengthen the implementation of vector control interventions, such as targeted indoor residual spraying, long-lasting insecticidal nets and other supplementary vector control measures such as larval source management and community engagement approaches. Furthermore, in low transmission settings, such as the Arjo Didessa Sugarcane Plantation, providing health education to local communities, enhanced environmental management and entomological surveillance, along with
case detection and management by targeting of malaria index cases and their immediate neighboring households, could be important measures to control residual malaria transmission and achieve the targeted elimination goals.