Abstract
The control of malaria vector mosquitoes in South Africa’s affected provinces is primarily based on indoor spraying of long-lasting residual insecticides. The primary vectors in South Africa are Anopheles arabiensis and An. funestus. South Africa’s National Malaria Control Programme has adopted a malaria elimination agenda and has scaled up vector control activities accordingly. However, despite these plans, local transmission continues and is most likely because of outdoor feeding by populations of An. arabiensis. An outdoor Anopheles surveillance system has been set up in three sections of the Mamfene district in northern KwaZulu- Natal in order to assess the extent of outdoor resting An. arabiensis in Mamfene and to assess the current insecticide susceptibility status of this population. According to WHO criteria, the An. arabiensis samples tested showed evidence of resistance to deltamethrin (pyrethroid), DDT (organochlorine) and bendiocarb (carbamate), and full susceptibility to the organophosphates pirimiphos-methyl and fenitrothion. Pre-exposure to piperonyl butoxide completely nullified the deltamethrin resistance otherwise evident in these samples, supporting previous studies implicating monooxygenase-based detoxification as the primary mechanism of pyrethroid resistance. The data presented here affirm the presence of pyrethroid and DDT resistance previously detected in this population and also indicate the comparatively recent emergence of resistance to the carbamate insecticide bendiocarb. These data show that special attention and commitment needs to be given to the principles of insecticide resistance management as well as to investigations into alternative control techniques designed to target outdoor-resting An. arabiensis in northern KwaZulu-Natal.
Highlights
The control of malaria vector mosquitoes in South Africa’s affected provinces is primarily based on indoor spraying of long-lasting residual insecticides.[1]
The malaria epidemic experienced in South Africa during the period 1996–2000 was largely the result of the development of resistance to pyrethroid insecticides in populations of this species in northern KwaZuluNatal and Mpumalanga which led to vector control failure.[1,2]
Control was re-established using a mosaic resistance management system which was later drafted into a World Health Organization (WHO) document –- the Global Plan for Insecticide Resistance Management (GPIRM).[4]
Summary
The control of malaria vector mosquitoes in South Africa’s affected provinces is primarily based on indoor spraying of long-lasting residual insecticides.[1] The indoor residual spraying (IRS) method has been the mainstay of malaria vector control in South Africa since the late 1940s and has remained effective owing to carefully co-ordinated IRS programmes in South Africa’s Limpopo, Mpumalanga and KwaZulu-Natal Provinces.[2]. Anopheles mosquitoes can transmit human malaria parasites and the primary vectors in South Africa are Anopheles arabiensis and An. funestus.[1] Of these, An. funestus is almost entirely anthropophilic (human biting), endophagic (indoor feeding) and endophilic (indoor resting).[3] These characteristics make this species especially susceptible to control by IRS, assuming that the insecticide employed for this purpose is effective against the target An. funestus population. Anopheles arabiensis is substantially less susceptible to control by IRS
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