High malaria transmission sustained by Anopheles gambiae s.l. occurring both indoors and outdoors in the city of Yaoundé, Cameroon

Patricia Doumbe-Belisse; Carmene Sandra Ngadjeu; Nadege Sonhafouo-Chiana; Abdou Talipouo; Landre Djamouko-Djonkam; Edmond Kopya; Roland Bamou; Jean Claude Toto; Souleyman Mounchili; Raymond Tabue; Parfait Awono-Ambene; Charles Sinclair Wondji; Flobert Njiokou; Christophe Antonio-Nkondjio

doi:10.12688/wellcomeopenres.14963.1

High malaria transmission sustained by Anopheles gambiae s.l. occurring both indoors and outdoors in the city of Yaoundé, Cameroon

Wellcome Open Res. 2018 Dec 23:3:164. doi: 10.12688/wellcomeopenres.14963.1. eCollection 2018.

Authors

Patricia Doumbe-Belisse^{1

2}, Carmene Sandra Ngadjeu^{1

2}, Nadege Sonhafouo-Chiana^{1

3}, Abdou Talipouo^{1

2}, Landre Djamouko-Djonkam^{1

4}, Edmond Kopya^{1

2}, Roland Bamou^{1

4}, Jean Claude Toto¹, Souleyman Mounchili², Raymond Tabue⁵, Parfait Awono-Ambene¹, Charles Sinclair Wondji⁶, Flobert Njiokou², Christophe Antonio-Nkondjio^{1

6}

Affiliations

¹ Malaria Research Laboratory, OCEAC, Yaoundé, Cameroon.
² University of Yaoundé 1, Yaoundé, Cameroon.
³ University of Buea, Buea, Cameroon.
⁴ University of Dschang, Dschang, Cameroon.
⁵ National Malaria Control Programme, Yaoundé, Cameroon.
⁶ Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.

Abstract

Background: Malaria remains a major public health problem in Cameroon; however, despite reports on the adaptation of anopheline species to urban habitats, there is still not enough information on malaria transmission pattern in urban settings. In the frame of a larval control trial in the city of Yaoundé, we conducted baseline surveys to assess malaria transmission dynamics in this city. Methods: Adult mosquitoes were collected indoors and outdoors using CDC light traps and human landing catches from March 2017 to March 2018 in 30 districts of Yaoundé, Cameroon. Mosquitoes were sorted by genus and identified to the species level using PCR. The TaqMan method and ELISA were used to determine mosquito infection status to Plasmodium. Bioassays were conducted to assess female Anopheles gambiae susceptibility to insecticides. Results: A total of 218,991 mosquitoes were collected. The main malaria vectors were An. gambiae s.l. (n=6154) and An. funestus s.l. (n=229). Of the 1476 An. gambiae s.l. processed by PCR, 92.19% were An. coluzzii and 7.81% An. gambiae. An. funestus s.l. was composed of 93.01% (173/186) An. funestus and 4.84% (13/186) An. leesoni. The average biting rate of anopheline was significantly high outdoor than indoor (P=0.013). Seasonal variation in mosquito abundance and biting rate was recorded. The infection rate by Plasmodium falciparum was 2.13% (104/4893 mosquitoes processed). The annual entomological inoculation rate was found to vary from 0 to 92 infective bites/man/year (ib/m/y). Malaria transmission risk was high outdoor (66.65 ib/m/y) compared to indoor (31.14 ib/m/y). An. gambiae s.l. was found highly resistant to DDT, permethrin and deltamethrin. High prevalence of the West Africa kdr allele 1014F was recorded and this was not found to influence An. gambiae s.l. infection status. Conclusion: The study suggests high malaria transmission occurring in the city of Yaoundé and call for immediate actions to improve control strategies.

Keywords: Anopheles; Cameroon; Malaria; Yaoundé; transmission; urbanization.

Grants and funding

This work received financial support from Wellcome Trust senior Fellowship in Public Health and Tropical Medicine (202687/Z/16/Z) to CAN.