Abstract:
Background: Insecticide resistance has emerged as one of the major challenges facing
National Malaria Control Programmes in Africa. A well-coordinated national database
on insecticide resistance (IRBase) can facilitate the development of effective strategies
for managing insecticide resistance and sustaining the effectiveness of chemical-based
vector control measures. The aim of this study was to assemble a database on the current
status of insecticide resistance among malaria vectors in Kenya.
Methods: Data was obtained from published literature through PubMed, HINARI and
Google Scholar searches and unpublished literature from government reports, research
institutions reports and malaria control programme reports. Each data source was
assigned a unique identification code and entered into Microsoft Excel 2010 datasheets.
Base maps on the distribution of insecticide resistance and resistance mechanisms among
malaria vectors in Kenya were generated using ArcGIS Desktop 10.1 (ESRI, Redlands,
CA, USA).
Results: Insecticide resistance status among the major malaria vectors in Kenya was
reported in all the four classes of insecticides including pyrethroids, carbamates,
organochlorines and organophosphates. Resistance to pyrethroids has been detected in
Anopheles gambiae (s.s.), An. arabiensis and An. funestus (s.s.) while resistance to
carbamates was limited to An. gambiae (s.s.) and An. arabiensis. Resistance to the
organochlorine was reported in An. gambiae (s.s.) and An. funestus (s.s.) while
resistance to organophosphates was reported in An. gambiae (s.l.) only. The mechanisms
of insecticide resistance among malaria vectors reported include the kdr mutations (L
1014S and L 1014F) and elevated activity in carboxylesterase, glutathione S-transferases
(GST) and monooxygenases. The kdr mutations L 1014S and L 1014F were detected in
An. gambiae (s.s.) and An. arabiensis populations. Elevated activity of monooxygenases
has been detected in both An. arabiensis and An. gambiae (s.s.) populations while the
elevated activity of carboxylesterase and GST has been detected only in An. arabiensis
populations.
Conclusions: The geographical maps show the distribution of insecticide resistance and
resistance mechanisms among malaria vectors in Kenya. The database generated will
provide a guide to intervention policies and programmes in the fight against malaria.