Malaria in South Africa is seasonal and primarily occurs in the Limpopo, Mpumalanga and KwaZuluNatal provinces. Malaria vectors are controlled by indoor spraying of residual insecticides (IRS) and limited larval source management. Vector surveillance in collaboration with the National Institute for Communicable Diseases (NICD) during 2021 revealed the presence of four malaria vector species – Anopheles arabiensis (n=4,873, 43%), An. merus (n=709, 6%), An. parensis (n=1,175, 10%) and An. vaneedeni (n=335, 3%). These have previously been shown to contribute to ongoing residual malaria transmission in South Africa. Several closely related non-vector Anopheles species were also collected.

The specimens analysed were collected from KwaZulu-Natal (69.7%, n=7,967), Mpumalanga (6.5%, n=747) and Limpopo (23.7%, n=2,714) provinces. The surveillance information by province and municipality shows that IRS-based vector control needs to be maintained at a high rate of coverage in high-incidence areas, and that spraying should ideally be completed before the onset of each malaria season. Consideration can be given to a more targeted or reactive approach in areas where no local cases have been recorded for three or more years. Given that all sporozoite positive (and therefore malaria infective) adult Anopheles females collected in the recent years were found resting outdoors, and given that there are no large-scale vector control tools targeting outdoor-resting mosquitoes, larviciding, including the treatment of winter breeding sites, should continue to be used as a complimentary method to enhance the effect of IRS in areas where locally-acquired cases occur and in other receptive areas at risk for malaria. Consideration should also be given to the distribution of dual active ingredient insecticide treated bed nets to migrant / mobile communities that are not protected by the IRS programmes.