Department of Medical Laboratory Science, School of Biomedical and Allied Health Sciences, University of Ghana, Korle-Bu, Accra, Ghana.
Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana.
Parasit Vectors. 2022 Jul 8;15(1):246. doi: 10.1186/s13071-022-05355-y.
In sub-Saharan Africa there is widespread use of long-lasting insecticidal nets and indoor residual spraying to help control the densities of malaria vectors and decrease the incidence of malaria. This study was carried out to investigate the resting behavior, host preference and infection with Plasmodium falciparum of malaria vectors in Ghana in the context of the increasing insecticide resistance of malaria vectors in sub-Saharan Africa.
Indoor and outdoor resting anopheline mosquitoes were sampled during the dry and rainy seasons in five sites in three ecological zones [Sahel savannah (Kpalsogo, Pagaza, Libga); coastal savannah (Anyakpor); and forest (Konongo)]. Polymerase chain reaction-based molecular diagnostics were used to determine speciation, genotypes for knockdown resistance mutations (L1014S and L1014F) and the G119S ace1 mutation, specific host blood meal origins and sporozoite infection in the field-collected mosquitoes.
Anopheles gambiae sensu lato (s.l.) predominated (89.95%, n = 1718), followed by Anopheles rufipes (8.48%, n = 162) and Anopheles funestus s.l. (1.57%, n = 30). Sibling species of the Anopheles gambiae s.l. revealed Anopheles coluzzii accounted for 63% (95% confidence interval = 57.10-68.91) and 27% (95% confidence interval = 21.66-32.55) was Anopheles gambiae s. s.. The mean resting density of An. gambiae s.l. was higher outdoors (79.63%; 1368/1718) than indoors (20.37%; 350/1718) (Wilcoxon rank sum test, Z = - 4.815, P < 0.0001). The kdr west L1014F and the ace1 mutation frequencies were higher in indoor resting An. coluzzii and An. gambiae in the Sahel savannah sites than in the forest and coastal savannah sites. Overall, the blood meal analyses revealed that a larger proportion of the malaria vectors preferred feeding on humans (70.2%) than on animals (29.8%) in all of the sites. Sporozoites were only detected in indoor resting An. coluzzii from the Sahel savannah (5.0%) and forest (2.5%) zones.
This study reports high outdoor resting densities of An. gambiae and An. coluzzii with high kdr west mutation frequencies, and the presence of malaria vectors indoors despite the use of long-lasting insecticidal nets and indoor residual spraying. Continuous monitoring of changes in the resting behavior of mosquitoes and the implementation of complementary malaria control interventions that target outdoor resting Anopheles mosquitoes are necessary in Ghana.
在撒哈拉以南非洲地区，广泛使用长效驱虫蚊帐和室内滞留喷洒来帮助控制疟疾媒介的密度并降低疟疾的发病率。本研究旨在调查在撒哈拉以南非洲地区疟疾媒介对杀虫剂的抗药性不断增强的情况下，加纳疟疾媒介的栖息行为、宿主偏好和疟原虫感染情况。
在五个地点的三个生态区[萨赫勒草原（Kpalsogo、Pagaza、Libga）；沿海草原（Anyakpor）；和森林（Konongo）]，在旱季和雨季采集室内和室外栖息的按蚊。聚合酶链反应（PCR）分子诊断用于确定物种、击倒抗性突变（L1014S 和 L1014F）和 ace1 基因突变（G119S）、特定宿主血液来源和现场采集蚊子中的孢子感染情况。
冈比亚按蚊复合体（s.l.）占主导地位（89.95%，n=1718），其次是鲁菲斯按蚊（8.48%，n=162）和芬尼斯按蚊复合体（1.57%，n=30）。冈比亚按蚊复合体的姐妹种显示，冈比亚按蚊 s.s.占 63%（95%置信区间=57.10-68.91），27%为冈比亚按蚊（Anopheles gambiae）s. s.（95%置信区间=21.66-32.55）。冈比亚按蚊 s.l.的平均栖息密度室外（79.63%；1368/1718）高于室内（20.37%；350/1718）（Wilcoxon 秩和检验，Z=-4.815，P<0.0001）。在萨赫勒草原地区的室内栖息的按蚊 coluzzii 和冈比亚按蚊中，kdr 西 L1014F 和 ace1 突变频率较高。总体而言，血液餐分析表明，在所有地点，疟疾病媒更喜欢以人类（70.2%）为食，而不是动物（29.8%）。仅在萨赫勒草原（5.0%）和森林（2.5%）地区的室内栖息的按蚊 coluzzii 中检测到孢子虫。
本研究报告了冈比亚按蚊和按蚊 coluzzii 的高室外栖息密度，以及高 kdr 西突变频率，尽管使用了长效驱虫蚊帐和室内滞留喷洒，但室内仍存在疟疾病媒。在加纳，有必要对蚊子的栖息行为变化进行持续监测，并实施针对室外栖息的按蚊的补充疟疾控制干预措施。
