How do imported malaria cases influence transmission and antimalarial drug resistance in South Africa’s elimination districts?
Malaria remains a major public health concern globally, despite being both preventable and curable. In 2024, an estimated 282 million malaria cases were reported worldwide, with Africa continuing to carry the overwhelming burden of disease transmission. South Africa, located at the southern edge of malaria transmission on the continent, has made substantial progress towards malaria elimination, particularly in the endemic provinces of Limpopo, Mpumalanga, and KwaZulu-Natal. However, persistent malaria importation from neighbouring higher-burden countries continues to threaten elimination efforts by sustaining local transmission and introducing drug-resistant parasites into low-transmission settings.
To accelerate progress towards elimination, South Africa has adopted a phased subnational elimination strategy, targeting districts with focused interventions aimed at interrupting residual transmission. Districts such as Ehlanzeni in Mpumalanga and uMkhanyakude in KwaZulu-Natal remain key areas of focus due to ongoing imported malaria cases and cross-border population movement. Imported infections not only increase the risk of secondary transmission but may also contribute to the spread of parasites carrying antimalarial drug-resistance mutations, potentially undermining treatment effectiveness in vulnerable communities with low immunity.
The following study compared the epidemiological characteristics, parasite species distribution, case detection methods, and prevalence of antimalarial drug-resistance markers among imported and locally acquired malaria cases reported between January 2022 and August 2024 in Ehlanzeni and uMkhanyakude districts.
The findings provide important insights to guide surveillance, case management, and targeted interventions in South Africa’s malaria elimination programme.
Materials and methods
We conducted a secondary, descriptive, comparative analytical study using data from routine genomic surveillance activities in Ehlanzeni District of the Mpumalanga province and uMkhanyakude District of the KwaZulu-Natal province between 2022 and 2024.
Routine genomic surveillance in these two districts involves the collection of used malaria rapid diagnostic tests(RDTs) and finger-prick filter paper dried blood spots (DBSs) from RDT-positive malaria cases detected through passive and active case detection.
Results
A total of 1 901 confirmed malaria cases, reported between January 2022 and August 2024, that met the case definition were successfully linked to their parasite genomic profiles and used in this analysis. The Ehlanzeni District in Mpumalanga accounted for 78% (1 483 /1 901) of the analysed cases, with the majority reported from Nkomazi Municipality (86%, 1 268/1 483). The 418 cases from uMkhanyakude District in KwaZulu-Natal were predominantly from the uMhlabuyalingana Municipality (46%, 191/418).
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