Consequences of insecticide resistance on malaria transmission

Résumé

Malaria burden and controlHuman malaria is caused by protozoan parasites of the genus Plasmodium (Plasmodium falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi).In 2015, 212 milion malaria cases were reported worldwide with approximately 429,000 deaths, 92% of which occured in Africa.However, several countries within sub-Saharan Africa have reported decreased numbers of malaria cases over the last several decades (http://www.who.int/malaria/publications/world-malaria- report-2016/en/).Plasmodium parasites are dependent on completing a complex life cycle in mosquitoes of the genus Anopheles, specifically, for transmission to occur.Thus, reducing the mosquito abundance or interfering with its ability to support the parasite cycle (i.e., the vector competence) can interrupt malaria transmission.However, not every species of Anopheles is a vector, and not all species of Plasmodium occur in all regions.In natural populations, the combination of Plasmodium-Anopheles species is very specific and leads to distinct epidemiology and transmission patterns.For example, the transmission of malaria parasites between humans is due primarly to the A. gambiae s.l.-P.falciparum combination, while in Southeast Asia, A. dirus and A. minimus-P.vivax are the main vectorial systems.This transmission potential between human hosts of a specific Anopheles population is characterized by the "vectorial capacity" and depends on the abundance, the feeding rate, the longevity, and the vector competence of female mosquitoes as well as the extrinsic incubation period of the parasite, which is the time for the pathogen to reach the transmissible stage from the midgut to the salivary glands of its vector.Between 2000 and 2015, the number of malaria infection deaths have been halved, with 79% of this reduction being attributed to insecticide-based vector control (insecticide-treated nets [ITNs] and indoor residual spraying [IRS]) [1].Therefore, insecticidebased vector control still represents the most important and affordable method to alleviate the malaria burden by interrupting the transmission cycle, although insecticide-resistance frequency and intensity have increased dramatically in malaria vector populations.In an attempt to explain this discrepancy, we present 5 facts about insecticide resistance in regards to malaria control when the epidemiological and ecological contexts are considered. The threat of insecticide resistanceOnly a few insecticides have been approved for public health, and, among them, only the pyrethroids are allowed for ITNs.Nowadays, resistance against this insecticide family is widespread among malaria vectors in Africa (see IR mapper [www.irmapper.com]for the latest update) and is expected to jeopardize the success of malaria control.According to the World Health

Citer ce document

Accès au document

Ce document est hébergé sur son dépôt institutionnel d'origine.

Auteur(s)

Statistiques

Consultations : 3

Téléchargements : 0