Implication of Anopheles funestus in malaria transmission in the city of Yaoundé, Cameroon

Landre Djamouko-Djonkam,Abdou Talipouo,Timoléon Tchuinkam,Diane Leslie Nkahe,Christophe Antonio-Nkondjio,Roland Bamou,Charles Sinclair Wondji,Edmond Kopya,Carmene Sandra Ngadjeu,Parfait Awono-Ambene,Patricia Doumbe-Belisse

doi:10.1051/parasite/2020005

Abstract

The contribution of Anopheles funestus to malaria transmission in the urban environment is still not well documented. The present study assesses the implication of An. funestus in malaria transmission in two districts, Nsam and Mendong, in the city of Yaoundé. Adult mosquitoes were collected using Centers for Disease Control and Prevention miniature light traps (CDC-LT) and human landing catches from April 2017 to March 2018 and were identified morphologically to the species level. Those belonging to the Anopheles gambiae complex and to the Anopheles funestus group were further processed by PCR to identify members of each complex/group. Anopheline mosquitoes were analysed to determine their infection status using an enzyme-linked immunosorbent assay. Bioassays were conducted with 2–5-day-old female Anopheles funestus and An. gambiae s.l. to determine their susceptibility to permethrin, deltamethrin and dichlorodiphenyltrichloroethane (DDT). Six anopheline species were collected in the peri-urban district of Mendong: Anopheles gambiae, An. coluzzii, An. funestus, An. leesoni, An. ziemanni and An. marshallii; only four out of the six were recorded in Nsam. Of the two members of the Anopheles gambiae complex collected, An. coluzzii was the most prevalent. Anopheles coluzzii was the most abundant species in Nsam, while An. funestus was the most abundant in Mendong. Both Anopheles funestus and An. gambiae s.l. were found to be infected with human Plasmodium at both sites, and both were found to be resistant to DDT, permethrin, and deltamethrin. This study confirms the participation of An. funestus in malaria transmission in Yaoundé and highlights the need to also target this species for sustainable control of malaria transmission.

Highlights

Anthropogenic changes affecting the environment, such as large-scale unplanned urbanisation, are considered to have a major influence on vector-borne disease epidemiology [27, 29, 31]
Studies conducted at the periphery of the city of Yaoundé reported the presence of vectors such as An. moucheti, An. nili, and An. funestus, which contribute alongside An. gambiae s.l. to malaria transmission [2]
Three species belonging to the An. funestus species group have been reported in Cameroon, including An. funestus, An. leesoni, and An. rivulorum [15]; only An. funestus is largely distributed across the country and has a major role in malaria transmission [2, 3, 11, 15]

Summary

Introduction

Anthropogenic changes affecting the environment, such as large-scale unplanned urbanisation, are considered to have a major influence on vector-borne disease epidemiology [27, 29, 31]. In Yaoundé, Anopheles gambiae and An. coluzzii are the most important malaria vectors in the city centre [56, 66]. Studies conducted at the periphery of the city of Yaoundé reported the presence of vectors such as An. moucheti, An. nili, and An. funestus, which contribute alongside An. gambiae s.l. to malaria transmission [2]. Anopheles funestus has always been reported in sympatry with An. gambiae in most rural settings in Cameroon [7, 10, 18] In some places, this vector was found to perpetuate high infection rates surpassing those of An. gambiae, demonstrating the important epidemiological role that it can play [16]. The role of An. funestus in malaria transmission in the city of Yaoundé was investigated during a survey comparing malaria transmission dynamics between a central and a peri-urban district

Methods

Results

Discussion

Conclusion