Changing distribution and abundance of the malaria vector Anopheles merus in Mpumalanga Province, South Africa.

Background: The malaria vector Anopheles merus occurs in the Mpumalanga Province of South Africa. As its contribution to malaria transmission in South Africa has yet to be ascertained, an intensification of surveillance is necessary to provide baseline information on this species. The aim of this study was therefore to map An. merus breeding sites in the Ehlanzeni District of Mpumalanga Province and to assess qualitative trends in the distribution and relative abundance of this species over a 9-year period. Methods: The study was carried out during the period 2005-2014 in the four high-risk municipalities of Ehlanzeni District. Fifty-two breeding sites were chosen from all water bodies that produced anopheline mosquitoes. The study data were extracted from historical entomological records that are captured monthly. Results: Of the 15 058 Anopheles mosquitoes collected, 64% were An. merus. The abundance and distribution of An. merus increased throughout the four municipalities in Ehlanzeni District during the study period. Conclusion: The expanded distribution and increased abundance of An. merus in the Ehlanzeni District may contribute significantly to locally acquired malaria in Mpumalanga Province, likely necessitating the incorporation of additional vector control methods specifically directed against populations of this species.

Contexte : Le vecteur du paludisme, Anopheles merus, sévit dans la province de Mpumalanga en Afrique du Sud. Comme sa contribution à la transmission du paludisme en Afrique du Sud reste à vérifier, une intensification de la surveillance est nécessaire afin de fournir des informations de départ sur cette espèce. Le but de cette étude a donc été de cartographier les sites de reproduction de An. merus dans le district d'Ehlanzeni de la province de Mpumalanga et d'évaluer les tendances qualitatives de la distribution et de l'abondance relative de cette espèce sur une période de 9 ans.Méthodes : Cette étude a été réalisée pendant la période de 2005 à 2014 dans les quatre municipalités à risque élevé du district d'Ehlanzeni. Cinquante-deux sites de reproduction ont été choisis dans tous les plans d'eau qui ont produit des moustiques de l'espèce anophèle. Les données de l'étude ont été extraites de registres entomologiques historiques qui sont saisis chaque mois.Résultats : Sur les 15 058 moustiques Anopheles recueillis, 64% ont été An. merus. L'abondance et la distribution d'An. merus ont augmenté dans les quatre municipalités du district d'Ehlanzeni pendant la période d'étude.Conclusion: La distribution en expansion et l'abondance accrue d'An. merus dans le district d'Ehlanzeni peut contribuer significativement au paludisme acquis localement dans la province de Mpumalanga et nécessite l'incorporation de méthodes de lutte vectorielle supplémentaires spécifiquement dirigées contre les populations de cette espèce.

Marco de referencia: Anopheles merus, vector del paludismo, está presente en la provincia de Mpumalanga de Suráfrica. Puesto que no se ha determinado su contribución a la transmisión del paludismo en el país, es necesario intensificar la vigilancia, con el fin de aportar información de referencia sobre esta especie. El objetivo del estudio fue cartografiar los criaderos de An. merus en el distrito de Ehlanzeni de la provincia de Mpumalanga y evaluar la evolución cuantitativa de la distribución y la abundancia relativa de esta especie durante un período de 9 años.Métodos: El estudio se llevó a cabo del 2005 al 2014 en cuatro municipios de alto riesgo de transmisión del distrito de Ehlanzeni. Se escogieron 52 criaderos de todas las masas de agua productoras de mosquitos anófeles. Los datos del estudio se extrajeron de los registros entomológicos históricos que se captan cada mes.Resultados: De los 15 058 mosquitos anófeles recogidos, el 64% correspondía a An. merus; su abundancia y distribución aumentó en los cuatro municipios del distrito de Ehlanzeni durante el período del estudio.Conclusión: La ampliación de la distribución y el aumento de la presencia de An. merus en el distrito de Ehlanzeni pueden contribuir de manera significativa a los casos de paludismo adquiridos localmente en la provincia de Mpumalanga, y es probable que sera necesario incorporar otros métodos de control de vectores dirigidos específicamente contra las poblaciones de esta especie.

Therapeutic efficacy of sulfadoxine-pyrimethamine for Plasmodium falciparum malaria.

OBJECTIVES: To assess the therapeutic efficacy of sulfadoxinepyrimethamine (SP) after 5 years of use as first-line treatment of uncomplicated Plasmodium falciparum malaria, and thus guide the selection of artemisinin-based combination therapy in Mpumalanga, South Africa. DESIGN: An open-label, in vivo therapeutic efficacy study of patients with uncomplicated P. falciparum malaria treated with a single oral dose of SP, with response to treatment monitored clinically and parasitologically on days 1, 2, 3, 7, 14, 21, 28 and 42. SETTING: Mangweni and Naas public health care clinics, Tonga district in rural Mpumalanga. SUBJECTS, OUTCOME MEASURES AND RESULTS: Of 152 patients recruited sequentially, 149 (98%) were successfully followed up for 42 days. One hundred and thirty-four patients (90%) demonstrated adequate clinical and parasitological response. Of the 15 patients (10%) who failed treatment, 2 (1.3%) had an early treatment failure, and polymerase chain reaction confirmed recrudescent infection in all 13 patients (8.7%) who had late parasitological (N = 11) or clinical (N = 2) failure. Gametocyte carriage was prevalent following SP treatment (84/152) and this has increased significantly since implementation in 1998 (relative risk 2.77 (confidence interval 1.65 - 4.66); p = 0.00004). CONCLUSION: Asexual P. falciparum parasites in Mpumalanga remain sensitive to SP, with no significant difference between the baseline cure rate (94.5%) at introduction in 1998, and the present 90% cure rate (p = 0.14). However, since gametocyte carriage has increased significantly we recommend that SP be combined with artesunate in Mpumalanga to reduce gametocyte carriage and thus decrease malaria transmission and potentially delay antimalarial resistance.

Using a geographical information system to plan a malaria control programme in South Africa.

INTRODUCTION: Sustainable control of malaria in sub-Saharan Africa is jeopardized by dwindling public health resources resulting from competing health priorities that include an overwhelming acquired immunodeficiency syndrome (AIDS) epidemic. In Mpumalanga province, South Africa, rational planning has historically been hampered by a case surveillance system for malaria that only provided estimates of risk at the magisterial district level (a subdivision of a province). METHODS: To better map control programme activities to their geographical location, the malaria notification system was overhauled and a geographical information system implemented. The introduction of a simplified notification form used only for malaria and a carefully monitored notification system provided the good quality data necessary to support an effective geographical information system. RESULTS: The geographical information system displays data on malaria cases at a village or town level and has proved valuable in stratifying malaria risk within those magisterial districts at highest risk, Barberton and Nkomazi. The conspicuous west-to-east gradient, in which the risk rises sharply towards the Mozambican border (relative risk = 4.12, 95% confidence interval = 3.88-4.46 when the malaria risk within 5 km of the border was compared with the remaining areas in these two districts), allowed development of a targeted approach to control. DISCUSSION: The geographical information system for malaria was enormously valuable in enabling malaria risk at town and village level to be shown. Matching malaria control measures to specific strata of endemic malaria has provided the opportunity for more efficient malaria control in Mpumalanga province.