Vector Population Monitoring Tool (VPMT)
Vector control programme managers need up to date information on mosquito populations to ensure that the interventions they plan are as effective as possible. Data on mosquito species, infection status and resistance to insecticides are vital elements in planning successful interventions. However, the current means of gathering this information is costly and inaccurate. Monitoring for each of these traits is currently performed using individual tests, some of which require sophisticated equipment and expensive consumables. Furthermore, these tests are not reliable for the detection of insecticide resistance at low levels.
The IVCC is funding the development of a simple molecular biology kit which will enable scientists in disease endemic countries to reliably identify the mosquito species, infection status (malaria positive or negative) and the presence of insecticide resistance genes by detecting a gene or sequence of DNA.
One example is resistance to pyrethroid insecticides. Gene mutation has resulted in the development of mosquito populations which are less vulnerable to insecticides. Bednets treated with pyrethroid insecticides are the primary method of malaria prevention in many countries so resistance to pyrethroids is of great concern for malaria control programmes. The first indication of resistance development is usually the failure of control programmes. The new kit is designed to screen the DNA of individual mosquitoes to determine whether they carry the resistance mutation, allowing programme managers to detect resistance earlier and crucially before control failure has occurred. This will give these health professionals more time to respond by changing insecticides or altering control strategies.
Following successful field trialling in Africa, VPMT protocols are now being used routinely in labs in South Africa to support the MDSS. A number of protocols have been published and are now available. Work will continue until the end of the current funding round in 2010 to identify novel markers of metabolic resistance in both Anopheles gambiae and Aedes aegypti from a range of field collected strains. Candidate resistance genes are still being identified, and tests and protocols being developed. The next funding round will commence in 2010, and will see the expansion of the VPMT into new regions and new malaria vectors.