Introduction: Malaria remains a significant public health concern in Mpumalanga Province, South Africa, despite sustained vector control interventions. Anopheles arabiensis is the primary malaria vector in the province. Understanding the relationship between malaria case trends and mosquito vector ecology is essential to guide elimination strategies. This study compared malaria incidence and vector patterns over two consecutive seasons, from April 2024 to March 2026.
Methods: An analysis of confirmed malaria cases reported to the District Health Information System (DHIS2) was conducted for April 2024–March 2025 and April 2025–March 2026. Entomological surveillance included routine mosquito collections at randomly selected sites using larval habitat sampling, clay pots, pit traps, house searches, direct catches, and baited nets. Vector species composition and density were analysed in relation to malaria case data using Microsoft Excel and DHIS2.
Results: In 2024/25, 1,068 total malaria cases were reported, including 66 local cases and three deaths. In 2025/26, total cases increased to 1,174, with 95 local cases and six deaths reported by the end of February 2026, reflecting a 10% increase in incidence. More than 90% of cases occurred in Ehlanzeni District, while Nkangala and Gert Sibande districts reported only imported cases. Imported infections accounted for most overall cases.
A total of 1,442 mosquitoes were collected in 2024/25, including 199 Anopheles gambiae complex larvae and 76 adults (84 An. arabiensis, 69 An. merus and 66 An. quadriannulatus). In 2025/26, 1,415 mosquitoes were collected, with 255 An. gambiae complex larvae and 21 adults (83 An. arabiensis, 165 An. merus and 24 An. quadriannulatus). Anopheles arabiensis remained the dominant vector, comprising 6% of collections in 2024/25 and 6% in 2025/26. Anopheles merus increased proportionally from 5% to 12% respectively.
Conclusion: Malaria incidence increased over the two-year period, coinciding with reduced An. arabiensis density and a relative rise in An. merus. The suspected shifts toward outdoor biting and the increasing proportion of An. merus suggest persistent residual transmission risk. Strengthened integrated vector management targeting outdoor transmission may reduce local cases and support elimination efforts.
