Vestergaard Frandsen and KEMRI/CDC have unveiled a mapping system to help fight malaria in sub-Saharan Africa. Developed by ESRI Eastern Africa, the IR Mapper is an interactive website that identifies locations where mosquitoes have developed resistance to the insecticides used in bed nets and indoor residual sprays. This includes more than 50 malaria-endemic countries. IR Mapper incorporates World Health Organization (WHO) revised criteria for reporting insecticide resistance. This allows the IR Mapper to direct which vector control tools should be deployed in areas of high resistance.
The mapping function allows filtering and projection of data based on a set of user-directed criteria. Data can be filtered by mosquito species and insecticide type for specific resistance profiles. Users can also track trends over time by selecting data from a particular period. Known mechanisms of resistance can also be presented visually on a map.
Resistance among Anopheles malaria vectors has been reported in 64 countries, with parts of Sub-Saharan Africa and India of greatest concern. “Deployment of the most appropriate insecticide based vector control interventions including nets and IRS needs to be informed by up-to-date data on insecticide resistance in the malaria vector species,” said Dr. Nabie Bayoh, an entomologist at KEMRI/CDC in Kisumu, Kenya. “Until now, data has been scattered throughout different databases and has come from a variety of sources. This has made prompt decision-making difficult.” he added.
Resistance is usually measured by putting mosquitoes in a tube lined with insecticide-treated paper. Mosquitoes land on the paper and absorb the insecticide – some may die and some may survive. A population is considered susceptible if almost all die. Until recently, resistance was confirmed by survival of more than 20 percent in this test. The new guidelines from WHO reduced this threshold value to 10 percent, meaning that resistance will be reported earlier. This change is an indication of the concern insecticide resistance is causing globally.
