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Problem Indoor residual spraying and long-lasting insecticidal nets (LLINs) are key tools for malaria vector control. Malawi has struggled to scale up indoor residual spraying and to improve LLIN coverage and usage. Approach In 2002, the Malawian National Malaria Control Programme developed guidelines for insecticide treated net distribution to reach the strategic target of at least 60% coverage of households with an LLIN. By 2005, the target coverage was 80% of households and the Global Fund financed the scale-up. The US President's Malaria Initiative funded the Indoor residual spraying intervention. Local setting Malawi's entire population is considered to be at risk of malaria. Poor vector control, insecticide resistance in malaria vectors and insufficient technical and financial support have exacerbated the malaria burden. Relevant changes Between 2002 and 2012, 18248206 LLINs had been distributed. The coverage of at least one LLIN per household Increased from 27% (3689/13664) to 58% (1974/3404). Indoor residual spraying coverage Increased from 28227 to 653592 structures between 2007 and 2011. However, vector resistance prompted a switch from pyrethroids to organophosphates for Indoor residual spraying, which increased the cost and operations needed to be cut back from seven to one district. Malaria cases increased from 2853315 in 2002 to 6 748 535 in 2010, and thereafter dropped to 4922 596 in 2012. Lessons learnt A single Intervention-based approach for vector control may have suboptlmal Impact. We 11-coordinated integrated vector management may offer greater benefits. A resistance management plan is essential for effective and sustainable vector control. Probleme La pulverisation d'insecticides a effet remanent a l'interieur des habitations et l'utilisation de moustiquaires a impregnation durable (MID) sont des mesures cles dans la lutte antivectorielle contre le paludisme. Mais le Malawi a eu du mal a intensifier les interventions de pulverisation intradomiciliaire d'insecticides et a ameliorer la protection par des MID et leur utilisation. Approche En 2002, le programme national de lutte contre le paludisme au Malawi a concu des directives pour distribuer des moustiquaires Impregnees d'insecticides en vue d'atteindre l'objectif strategique d'au moins 60% des menages utilisant une MID. En 2005, la couverture ciblee est passee a 80% des menages, et le Fonds mondial a finance l'intensification de la campagne. Les interventions de pulverisation intradomiciliaire d'insecticides a effet remanent ont ete financees par l'Initiative du President des Etats-Unis contre le paludisme. Environnement local On considere que l'integralite de la population du Malawi est exposee au risque palustre. Mais une lutte antivectorielle deficiente, le developpement d'une resistance aux insecticides chez les vecteurs du paludisme et un soutien technique et financier insuffisant ont aggrave la charge du paludisme. Changements significatifs Entre 2002 et 2012,18 248 206 MID ont ete distribuees. L'utilisation d'au moins une MID dans chaque menage est passee de 27% (3 689/13 664) a 58% (1 974/3 404). La couverture par pulverisation intradomiciliaire a effet remanent est passee de 28 227 a 653 592 structures entre 2007 et 2011. Neanmoins, la resistance des vecteurs aux insecticides a necessite d'abandonner les pyrethrinoides au profit des organophosphores pour les pulverisations Intradomiciliaires, ce qui a majore les couts et necessite de limiter les interventions a un seul district, sur les sept initialement prevus. Les cas de paludisme ont augmente de 2 853 315 en 2002 a 6 748 535 en 2010 avant de chuter a 4 922 596 en 2012. Lecons tirees En matiere de lutte antivectorielle, une approche fondee sur un seul type d'intervention peut avoir des effets sous-optimaux. Une gestion antivectorielle Integree correctement coordonnee pourrait etre plus benefique. Un plan de gestion de la resistance est essentiel pour une lutte antivectorielle efficace et durable. Situacion La fumigacion de interiores con accion residual y los mosquiteros tratados con insecticidas de larga duracion (LLIN, por sus siglas en ingles) son herramientas importantes para el control de vectores de la malaria. Malawi ha luchado por aumentar la fumigacion de interiores con accion residual y por mejorar te cobertura y uso de los LLIN. Enfoque En 2002, el Programa de Control Nacional contra la Malaria de Malawi desarrollo directrices para la distribucion de mosquiteros tratados con insecticidas con el fin de alcanzar el objetivo estrategico de que como minimo el 60% de los hogares dispusieran de un LLIN. En 2005, la cobertura objetivo era un 80% de los hogares y el Fondo Mundial financio la ampliacion. La Iniciativa del Presidente de los Estados Unidos de America contra la Malaria financio la intervencion de la fumigacion de interiores con accion residual. Marco regional Se considera que toda la poblacion de Malawi corre el riesgo de sufrir malaria. Los escasos controles de vectores, la resistencia de los insecticidas en los vectores de la malaria y el apoyo tecnico y financiero Insuficiente han multiplicado las tasas de malaria. Cambios importantes Entre 2002 y 2012, se han distribuido 18 248 206 LLIN. La cobertura de al menos un LLIN por hogar ha aumentado de un 27% (3 689/13 664) aun 58% (1 974/3 404). La cobertura de fumigacion de interiores con accion residual ha aumentado de 28 227 a 653 592 estructuras entre 2007 y 2011. No obstante, la resistencia de vectores ha acelerado un cambio de piretroldesa organofosfatos para la fumigacion de interiores con accion residual, lo que ha aumentado el coste y las operaciones necesarias para reducir de siete distritos a uno. Los casos de malaria aumentaron de 2 853 315 en 2002 a 6 748 535 en 2010, y luego cayeron a 4 922 596 en 2012. Lecciones aprendidas Un enfoque basado en una unica Intervencion para el control de vectores puede tener un impacto suboptimo. Una gestion integrada de vectores bien coordinada puede ofrecer mayores beneficios. Es fundamental desarrollar un plan de gestion de resistencia para lograr un control de vectores eficaz y sostenible., Introduction Malaria remains an important cause of morbidity and mortality. Approximately 214 million malaria cases and 438 000 malaria-related deaths were reported globally in 2015. The highest burden is seen [...]

Abstract Background Although malaria is highly prevalent throughout Malawi, little is known of its transmission dynamics. This paper describes the seasonal activity of the different vectors, human biting indices, sporozoite rates and the entomological inoculation rate in a low-lying rural area in southern Malawi. Methods Vectors were sampled over 52 weeks from January 2002 to January 2003, by pyrethrum knockdown catch in two villages in Chikhwawa district, in the Lower Shire Valley. Results In total, 7,717 anophelines were collected of which 55.1% were Anopheles gambiae sensu lato and 44.9% were Anopheles funestus. Three members of the An. gambiae complex were identified by PCR: Anopheles arabiensis (75%) was abundant throughout the year, An. gambiae s.s. (25%) was most common during the wet season and Anopheles quadriannulatus occurred at a very low frequency (n=16). An. funestus was found in all samples but was most common during the dry season. Anopheles gambiae s.s. and An. funestus were highly anthropophilic with human blood indices of 99.2% and 96.3%, respectively. Anopheles arabiensis had fed predominantly on humans (85.0%) and less commonly on cattle (10.9%; 1.2% of blood meals were of mixed origin). Plasmodium falciparum (192/3,984) and Plasmodium malariae (1/3,984) sporozoites were detected by PCR in An. arabiensis (3.2%) and An. funestus (4.5%), and in a significantly higher proportion of An. gambiae s.s. (10.6%)(pP. falciparum sporozoite rate was 4.8%, resulting in estimated inoculation rates of 183 infective bites/ person per annum, or an average rate of ~15 infective bites/person/month. Conclusions The results demonstrate the importance of An. gambiae s.s., An. arabiensis and An. funestus in driving the high levels of malaria transmission in the south of Malawi. Sustained and high coverage or roll out of current approaches to malaria control (primarily insecticide-treated bed nets and indoor residual house spraying) in the area are likely to reduce the observed high malaria transmission rate and consequently the incidence of human infections, unless impeded by increasing resistance of vectors to insecticides.