Ecology of breeding sites and insecticide resistance of the potential malaria vectors in Mpumalanga Province, South Africa

In spite of the reduction of morbidity and mortality rates reported recently, malaria remains a problematic disease in sub-Saharan Africa. An estimated 184 million people contracted the disease in 2010 with 611,000 deaths in the African region. Its transmission is sustained by the presence of highly efficient and anthropophilic Anopheles vector mosquitoes despite the continuous use of indoor residual spraying (IRS) and insecticide treated bed nets that have reduced the burden of malaria in some regions. The Anopheles funestus group and the An. gambiae complex contain the three most efficient vectors responsible for malaria transmission and are distributed across most of subSaharan Africa. In Mpumalanga Province of South Africa, 85% of the malaria cases are imported and only 15% are acquired locally. This study aimed to review and update the entomological data on breeding sites of potential malaria vectors and to investigate the insecticide resistance status of these mosquitoes in Mpumalanga Province. The study was conducted in the Ehlanzeni district around the low and high risk areas of Nkomazi municipality. The study was carried out from October – December 2011 .Selected breeding sites were monitored and all larvae sampled were reared to adults. One to five-day old female mosquitoes were used for insecticide susceptibility tests according to the WHO standard procedures. Female mosquitoes were morphologically identified and PCR was performed for members of the An. gambiae complex and the An. funestus group. in Twenty-five permanent mosquito breeding sites were mapped with 60% located in the high risk areas and 40% in the low risk areas. A total of 1200 anopheline mosquitoes were collected with 82.5% belonging to the An. gambiae complex and 27.5% belonging to the An. funestus group. 365 specimens were subjected to PCR for species-specific identification Anopheles merus and An. rivulorum were the most abundant species. Mosquitoes were subjected to the WHO insecticide resistance tests and were susceptible to all tested residual insecticides with an average of 99% mortality. Additional mosquito collection methods, such as night-biting catches, carbon dioxide net traps and pit-trap collections need to be carried out to sample other proportions of the mosquito populations that may not have been sampled by larval collections.

Insecticide Resistance
Vector Control

May 2013

South Africa