Abstract

Malaria is a global public health problem, with about 3.2 billion people at risk of infection. The populations at risk mainly reside in Africa, Asia and America, with African populations accounting for the largest burden of the disease. In 2013, close to 198 million malaria cases were reported, leading to 584,000 deaths. Much (90 %) of the mortality rates were recorded from the World Health Organization (WHO) database in the African region and 78 % of these occurred in children under the age of five. In Zimbabwe, approximately half of the population is at risk of infection with malaria.Insecticide residual spraying (IRS) has been documented as an effective way to control malaria and has been adopted globally by the WHO and national governments. However, both insecticide resistance and climate change threaten to reverse the progress made by IRS in malaria control. Resistance has been reported in all four classes of insecticides approved by the WHO for vector control intervention. Variability of environmental temperature is suspected to complicate the situation through alteration in the genetic structure, and enzyme and protein profiles of mosquitoes. In Zimbabwe, little research has been done on the interaction between climate change, temperature variability and insecticide resistance in malarial mosquitoes over time. Such information is important for informing policies on insecticide selection for IRS.We reviewed literature on insecticide sensitivity among malarial mosquitoes in Zimbabwe from 1972 to 2014. International peer-reviewed articles on insecticide sensitivity in Zimbabwe, published in English in this time period, were searched using MEDLINE® (PubMed), Google Scholar, Google and grey literature. Eight publications were eligible for the present study, with one of the articles being a review paper. Six articles covered insecticide resistance, while the other two articles, published in 2000, were about the absence of resistance. Contradicting resistance results were reported in 2014.The insecticide sensitivity status and distribution of insecticide resistance in mosquitoes are still under debate in Zimbabwe, as studies report differing results. The resistance trend in Zimbabwe is characterised by fluctuations in the status of the sensitivity of existing insecticides. Inconsistencies in data collection methods may be responsible for the inconsistencies in the results. None of the studies have determined a link between climate/temperature variability and insecticide resistance as yet. The current insecticide sensitivity status of mosquitoes still needs to be verified.

Highlights

  • Malaria is a vector-borne disease endemic in tropical and subtropical areas [1]

  • History of insecticide use in malaria control in Zimbabwe DDT was the first insecticide to be used in Insecticide residual spraying (IRS) in Greece in 1947, by 1951 the insecticide had been effectively used in 22 countries [45]

  • Following the discovery of benzene hexachloride (BHC) resistance in An. arabiensis mosquitoes in the Chiredzi district, BHC was replaced with DDT [48]

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Summary

Introduction

Malaria is a vector-borne disease endemic in tropical and subtropical areas [1]. In 2013, an estimated 584,000 deaths from malaria were reported worldwide, with most (90 %) of the deaths occurring in the African region (as recorded in the World Health Organization [WHO] database). Zimbabwe has a population of about 13 million [3], with half of that population living in malaria-endemic areas [4, 5]. Anopheles arabiensis Patton and Anopheles gambiae sensu stricto Giles mosquitoes are responsible for the transmission of malaria in the country [6, 7], with An. arabiensis mosquitoes responsible for the majority of the transmission [7, 8]. The advent of climate change, especially increases in temperature, threatens to complicate the situation by extending the geographical distribution of malaria globally [9], in parts of Europe [10], Asia [11] and Africa [12,13,14]

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