Dynamics and monitoring of insecticide resistance in malaria vectors across mainland Tanzania from 1997 to 2017: a systematic review
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Date
2019-03
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central (BMC)
Abstract
Background: Malaria still claims substantial lives of individuals in Tanzania. Insecticide-treated nets (ITNs) and indoor
residual spray (IRS) are used as major malaria vector control tools. These tools are facing great challenges from the
rapid escalating insecticide resistance in malaria vector populations. This review presents the information on the
dynamics and monitoring of insecticide resistance in malaria vectors in mainland Tanzania since 1997. The information is important to policy-makers and other vector control stakeholders to refect and formulate new resistance
management plans in the country.
Methods: Reviewed articles on susceptibility and mechanisms of resistance in malaria vectors to insecticides across
mainland Tanzania were systematically searched from the following databases: PubMed, Google scholar, HINARI and
AGORA. The inclusion criteria were articles published between 2000 and 2017, reporting susceptibility of malaria
vectors to insecticides, mechanisms of resistance in the mainland Tanzania, involving feld collected adult mosquitoes,
and mosquitoes raised from the feld collected larvae. Exclusion criteria were articles reporting insecticide resistance
in larval bio-assays, laboratory strains, and unpublished data. Reviewed information include year of study, malaria vectors, insecticides, and study sites. This information was entered in the excel sheet and analysed.
Results: A total of 30 articles met the selection criteria. The rapid increase of insecticide resistance in the malaria
vectors across the country was reported since year 2006 onwards. Insecticide resistance in Anopheles gambiae sensu
lato (s.l.) was detected in at least one compound in each class of all recommended insecticide classes. However, the
Anopheles funestus s.l. is highly resistant to pyrethroids and DDT. Knockdown resistance (kdr) mechanism in An. gambiae s.l. is widely studied in the country. Biochemical resistance by detoxifcation enzymes (P450s, NSE and GSTs) in An.
gambiae s.l. was also recorded. Numerous P450s genes associated with metabolic resistance were over transcribed in
An. gambiae s.l. collected from agricultural areas. However, no study has reported mechanisms of insecticide resistance in the An. funestus s.l. in the country.
Conclusion: This review has shown the dynamics and monitoring of insecticide resistance in malaria vector populations across mainland Tanzanian. This highlights the need for devising improved control approaches of the malaria
vectors in the country.
Description
Keywords
Anopheles funestus, Anopheles gambiae, Insecticides, Resistance, Malaria, Vector control, Tanzania