<i>Anopheles leesoni</i>Evans 1931, a Member of the <i>Anopheles funestus</i>Group, Is a Potential Malaria Vector in Cameroon

Background: Understanding the biology of Anopheles malaria vector species is essential to planning effective and sustainable malaria control strategies in endemic countries. This study reported the implication of Anopheles leesoni in malaria transmission in Cameroon, Central Africa. Methods: Mosquitoes were collected in three localities from May 2015 to March 2018 using electric aspirators and Centers for Disease Control light traps (CDC-LT). Anopheles funestus sensu lato (s.l.) mosquitoes were identified as species using polymerase chain reaction assay (PCR). Furthermore, Plasmodium falciparum infection status was determined using the enzyme-linked immunosorbent assay (ELISA) method. Results: A total of 12,744 Anopheles mosquitoes were collected by electric aspirator (N = 4844) and CDC-LT (N = 7900). Anopheles funestus s.l. (86.95%) was the major species and the main malaria vector in rural savannah and rural forest sites followed by A. gambiae s.l. (13.05%) whereas in urban areas, A. gambiae s.l. was by far the most abundant representing 91.45% of Anopheles mosquitoes collected. Two members of the A. funestus group were identified among 1389 analysed by PCR: 1307 A. funestus sensu stricto (s.s.) (94.10%) and 82 A. leesoni (5.9%). Plasmodium falciparum infection rate was 21.04% in A. funestus s.s. For the first time, A. leesoni was found positive for P. falciparum (infection rate: 10.98%) in Cameroon. Conclusion: A very high P. falciparum infection rate was observed in this study in A. funestus s.s., highlighting its high implication in malaria transmission in Cameroon. Furthermore, the detection of P. falciparum infection in A. leesoni calls for more attention towards this neglected vector species.

Modelling of the Abundance of Malaria Mosquitoes Using Poisson Mixed Model

Anopheles funestus and Anopheles gambiae are malaria vector mosquitoes. Knowing their resting behavior is important for implementing control methods. The aim of this study was to investigate the resting behaviour of the two malaria mosquitoes. The study was conducted in Kilombero River Valley and mosquitoes were collected using indoor and outdoor traps from 2012-2015. Poisson mixed models were used to quantify the impact of environment variables on resting behaviour. A log ratio rate between the type of trap and its interaction with environmental variables was used to determine if there was a change over time in the resting behaviour. A total of 4696 mosquitoes were resting indoors of which 57% were A. funestus and 43% were A. gambiae. Similarly, a total of 12,028 mosquitoes were resting outdoor of which 13% were A. funestus and 87% were A. gambiae. Temperature was significant and affected the resting behaviour of A. funestus. Humidity, saturation deficit and temperature were significant variables influencing the resting behaviour of A. gambiae. A. funestus was resting indoor while A. gambiae was resting outdoor over time generally. The findings of this study on the effects of environmental variables and the variations in the resting behaviour of A. gambiae and A. funestus could be used as a guide to implementing appropriate intervention measures such as indoor residential spraying (IRS), insecticide treated nets (ITNs) and mosquito repellents.

Spatial distribution and habitat characterization of mosquito species during the dry season along the Mara River and its tributaries,in Kenya and Tanzania

Background:Vector-borne diseases are increasingly becoming a major health problem among communities living along the major rivers of Africa.Although larger water bodies such as lakes and dams have been extensively researched,rivers and their tributaries have largely been ignored.This study sought to establish the spatial distribution of mosquito species during the dry season and further characterize their habitats along the Mara River and its tributaries.Methods:In this cross-sectional survey,mosquito larvae were sampled along the Mara River,its two perennial tributaries(Amala and Nyangores),drying streams,and adjacent aquatic habitats(e.g.swamps,puddles that receive direct sunlight[open sunlit puddles],rock pools,hippo and livestock hoof prints,and vegetated pools).Each habitat was dipped 20 times using a standard dipper.Distance between breeding sites and human habitation was determined using global positioning system coordinates.The collected mosquito larvae were identified using standard taxonomic keys.Water physico-chemical parameters were measured in situ using a multiparameter meter.Mean mosquito larvae per habitat type were compared using analysis of variance and chi-square tests,while the relationship between mosquito larvae and physicochemical parameters was evaluated using a generalized linear mixed model.The Cox-Stuart test was used to detect trends of mosquito larvae distribution.The test allowed for verification of monotonic tendency(rejection of null hypothesis of trend absence)and its variability.Results:A total of 4001 mosquito larvae were collected,of which 2712(67.8%)were collected from river/stream edge habitats and 1289(32.2%)were sampled from aquatic habitats located in the terrestrial ecosystem about 50 m away from the main river/streams.Anopheles gambiae s.s,An.arabiensis,and An.funestus group,the three most potent vectors of malaria in Sub-Saharan Africa,together with other anopheline mosquitoes,were the most dominant mosquito species(70.3%),followed by Culex quinquefasciatus and Cx.pipiens complex combined(29.5%).Drying streams accounted for the highest number of larvae captured compared to the other habitat types.A stronger relationship between mosquito larvae abundance and dissolved oxygen(Z=7.37,P≤0.001),temperature(Z=7.65,P≤0.001),turbidity(Z=−5.25,P≤0.001),and distance to the nearest human habitation(Z=4.57,P≤0.001),was observed.Conclusions:Presence of malaria and non-malaria mosquito larvae within the Mara River basin calls for immediate action to curtail the insurgence of vector-borne diseases within the basin.A vector control program should be conducted during the dry period,targeting drying streams shown to produce the highest number of larval mosquitoes.

Lymphatic filariasis, infection status in Culex quinquefasciatus and Anopheles species after six rounds of mass drug administration in Masasi District, Tanzania

Background:Lymphatic filariasis(LF)elimination program in Tanzania started in 2000 in response to the Global program for the elimination of LF by 2020.Evidence shows a persistent LF transmission despite more than a decade of mass drug administration(MDA).It is advocated that,regular monitoring should be conducted in endemic areas to evaluate the progress towards elimination and detect resurgence of the disease timely.This study was therefore designed to assess the status of Wuchererio bancrofti infection in Culex quinqefasciatus and Anopheles species after six rounds of MDA in Masasi District,South Eastern Tanzania.