Anopheles gambiae s.l trophic and resting behaviour in urban and sub urban areas of North Cameroon: routes for residual malaria transmission.

CaHReF 20116, Yaoundé Conges hall, 23 – 26 August 2016 , PL041

During the past decade, approximately 289 million LLINs were provided in sub-Saharan Africa, and they covered around 76% of the estimated 765 million people at risk of malaria. However, the effectiveness of these nets faces numerous challenges among which insecticide resistance and behavioural adaptation of malaria vectors. The current study aims at investigating trophic and resting behaviours of three major malaria vectors belonging to the Anopheles gambiae complex, in the Northern Cameroon context of insecticide resistance and wide use of LLINs. 

Two cross sectional entomological surveys were conducted in 2011 and 2012, across 28 clusters selected in 2 health districts (Garoua urban & Pitoa sub urban areas) of North Cameroon. Adult Anophelines were collected via 3 methods: window exit traps, clay pots that served as outdoor shelters and indoor spray catches with pyrethroids. Collected mosquitoes were morphologically identified and molecularly via PCR-RFLP. ELISA tests were carried out to determine the origin of vector blood meals their anthropophilic rates and also to determine their infectivity.

Data from this study reveals that An. arabiensis, An. coluzzii and An. gambiae of the Gambiae complex readily rest indoors as well as outdoors in Garoua and Pitoa health districts in North Cameroon. In total, 1280 An. gambiae s.l were collected, with An. arabiensis being the dominant sibling species within the two health districts (70-98%). The majority of the specimens were collected indoors (47-63%). Overall, more specimens were fed versus unfed, humans were the preferred host(45%) versus 17.8% with mixed blood meals among humans and other hosts (mainly cattle) and 19% mixed blood meals among animals only. The mean anthropophilic rates were 62-70% in Garoua, and 56-64% in Pitoa. There was a tendency of a drop in the anthropophilic rates of the 3 sibling species from 2011 to 2012 (p= 0.04). 

The current study provides evidence of An. arabiensis, An. gambiae and An. colluzii behaviour plasticity in North Cameroon. Research on new vector control options are therefore needed to control outdoor and residual malaria transmission in this Region.

Malaria, An.gambiae s.l, Behaviour, Host diversity