Tessy Igomu
Indiscriminate use of pesticide and insecticide for agricultural as well as public health programmes have been linked to moderate and high-intensity resistance developed by Anopheles mosquitoes in Africa, a study has revealed
The study, published in Scientific Reports, a peer-reviewed journal, stated that Anopheles gambiae, the most significant malaria vector in Africa, is developing increasing resistance, especially to synthetic pyrethroid insecticides, commonly used for controlling malaria causing mosquitoes worldwide.
The team of researchers drawn from Kenya, Ghana and the US, revealed that the study was carried out using samples of mosquitoes collected from west Kenya, adding that they analyzed the results of a variety of tests, including exposing the mosquitoes to insecticides through several generations.
They noted that while the younger generations showed greater insecticide resistance, it was discovered that reducing the use of the chemicals for at least 15 generations decreased the level of resistance.
The lead author, Maxwell Machani, an entomology expert at the Kenya Medical Research Institute, said the reduction in use of chemicals restored the mosquitoes’ vulnerability to the pyrethroid insecticides in a process that takes an average of two years.
“Public health authorities should rotate insecticides every year to beat mosquito resistance,” he added.
However, Maria Anice Mureb Sallum, a professor at the University of São Paulo’s public health faculty, said deeper research is needed to generalize the findings.
“Other An. gambiae populations could be tested in other regions of Africa with more varied insecticide exposure to see if the same mechanism works,” she advised.
According to the World Health Organisation, Malaria is a life-threatening disease caused by Plasmodium parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes, adding that it is preventable and curable.
The WHO noted that the parasites are spread to people through the bites of infected female Anopheles mosquitoes.
The global health body revealed that in 2019, there were an estimated 229 million cases of malaria worldwide, and that the estimated number of malaria deaths stood at 409 000 in 2019.
“Children aged under 5 years are the most vulnerable group affected by malaria; in 2019, they accounted for 67 per cent (274 000) of all malaria deaths worldwide.
“The WHO African Region carries a disproportionately high share of the global malaria burden.
“In 2019, the region was home to 94 per cent of malaria cases and deaths,” the WHO stated.
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