Email updates

Keep up to date with the latest news and content from BMC Infectious Diseases and BioMed Central.

Open Access Research article

Bionomics of Anopheline species and malaria transmission dynamics along an altitudinal transect in Western Cameroon

Timoléon Tchuinkam12*, Frédéric Simard24, Espérance Lélé-Defo1, Billy Téné-Fossog3, Aimé Tateng-Ngouateu1, Christophe Antonio-Nkondjio2, Mbida Mpoame1, Jean-Claude Toto2, Thomas Njiné3, Didier Fontenille4 and Herman-Parfait Awono-Ambéné2

Author Affiliations

1 Laboratory of Applied Biology and Ecology (LABEA), Department of Animal Biology, Faculty of Sciences of the University of Dschang, PO Box 067 Dschang, Cameroon

2 Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), BP 288 Yaoundé, Cameroon

3 Hydrobiology laboratory, Faculty of Sciences of the University of Yaounde I, PO Box 812 Yaounde, Cameroon

4 Laboratoire de Lutte contre les Insectes Nuisibles (LIN-UR 016), Institut de Recherche pour le Développement (IRD), 911 Av Agropolis, BP 64501, 34394 Montpellier, France

For all author emails, please log on.

BMC Infectious Diseases 2010, 10:119  doi:10.1186/1471-2334-10-119

Published: 19 May 2010

Abstract

Background

Highland areas of Africa are mostly malaria hypoendemic, due to climate which is not appropriate for anophelines development and their reproductive fitness. In view of designing a malaria control strategy in Western Cameroon highlands, baseline data on anopheline species bionomics were collected.

Methods

Longitudinal entomological surveys were conducted in three localities at different altitudinal levels. Mosquitoes were captured when landing on human volunteers and by pyrethrum spray catches. Sampled Anopheles were tested for the presence of Plasmodium circumsporozoite proteins and their blood meal origin with ELISA. Entomological parameters of malaria epidemiology were assessed using Mac Donald's formula.

Results

Anopheline species diversity and density decreased globally from lowland to highland. The most aggressive species along the altitudinal transect was Anopheles gambiae s.s. of S molecular form, followed in the lowland and on the plateau by An. funestus, but uphill by An. hancocki. An. gambiae and An. ziemanni exhibited similar seasonal biting patterns at the different levels, whereas different features were observed for An. funestus. Only indoor resting species could be captured uphill; it is therefore likely that endophilic behaviour is necessary for anophelines to climb above a certain threshold. Of the ten species collected along the transect, only An. gambiae and An. funestus were responsible for malaria transmission, with entomological inoculation rates (EIR) of 90.5, 62.8 and zero infective bites/human/year in the lowland, on the plateau and uphill respectively. The duration of gonotrophic cycle was consistently one day shorter for An. gambiae as compared to An. funestus at equal altitude. Altitudinal climate variations had no effect on the survivorship and the subsequent life expectancy of the adult stage of these malaria vectors, but most probably on aquatic stages. On the contrary increasing altitude significantly extended the duration of gonotrophic cycle and reduced: the EIR, their preference to human blood and consequently the malaria stability index.

Conclusion

Malaria epidemiological rooting in the outskirts of Western Cameroon highlands evolves with increasing altitude, gradually from stable to unstable settings. This suggests a potential risk of malaria epidemic in highlands, and the need for a continuous epidemiological surveillance.