TANZANIA – A new insecticide chlorfenapyr has been found to be effective in killing female anopheles mosquitoes when used on mosquito nets alongside traditional chemicals pyrethroids.
The insecticide was subjected to a large trial in Tanzania involving 39,000 Tanzanian households with over 4,500 children aged six months to 14 years.
Under the study, the mosquito net was loaded with Chlorfenapyr, the first new class of insecticide approved to fight malaria in 40 years, and pyrethroids which are commonly used to coat traditional mosquito nets.
The study found out that lacing bed nets with a combination of chlorfenapyr and pyrethroid significantly reduces malaria incidence including in regions where insecticide resistance is widespread
The research was carried out by the London School of Hygiene and Tropical Medicine, the National Institute for Medical Research and Kilimanjaro Christian Medical University College in Tanzania in collaboration with the University of Ottawa.
The rollout of insecticide-treated bed nets has been central in efforts to reduce the spread of malaria which remains one of the world’s deadliest infectious diseases.
The nets covered with traditional pyrethroids have contributed greatly to reducing the impact of malaria in sub-Saharan Africa for the past decade.
However, there’s been a slowdown of that trend more recently because the Anopheles mosquitoes responsible for the spread of malaria have become increasingly resistant to the pyrethroid insecticides.
Pyrethroids which were developed in the 1980s paralyze mosquitoes by targeting their nervous system while Chlorfenapyr triggers wing muscle cramps essentially grounding mosquitoes and eventually killing them.
The double coated netting seeks to address the challenge of growing mosquito resistance to traditional, widely used insecticide nets and traps through applying a different mechanism to avoid any type of cross-resistance.
The recent research revealed that the new mosquito grounding insecticide reduced cases of malaria in children by about 40 per cent.
In randomized trials using ecological models of carrier species, the mosquito net coated with chlorfenapyr immobilized the insects making them unable to bite humans thus reducing the prevalence of malaria by 43 per cent in the first year and 37 per cent in the second.
The investigation has shown that the double-coated netting also reduced clinical episodes of malaria by 44 per cent over the two-year study period.
It further revealed that the new type of net that has two insecticides was very successful at reducing malaria infection in children in areas with insecticide resistance in the malaria mosquito population.
“By testing out new types of dual-insecticide treated nets, we were able to see if any of these new nets were effective at controlling malaria in areas with resistant mosquitoes,” said Dr. Manisha Kulkarni, an associate professor in the school of epidemiology and public health at the University of Ottawa.
The new long-lasting type of nets are more expensive than the old ones but researchers estimate that there will be a reduction in costs for the health system making the extra cost invaluable.
Further research is still underway to determine whether the nets can be produced on a larger scale, to develop strategies to reduce the insects’ resistance to the new insecticide and to keep the nets effective long-term.
The advanced nets will be tested in the Republic of Benin to study their effectiveness in a different context which could ultimately lead to their recommendation by the World Health Organization.
The new weapon against the female anopheles mosquitoes alongside the malaria vaccine which was approved in 2021 could greatly contribute to malaria control in the African continent.
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