A group of scientists from various Asian countries found mosquitoes highly resistant to common insecticides, both in Vietnam and Cambodia. This isn’t the first time a similar finding has been made, however, as other scientists warned a few months ago that disease-carrying mosquitoes, equally resistant to pesticides, were arriving in Ethiopia.
Mosquito transmit a large number of infectious diseases, From dengue and yellow fever to Zika virus and malaria. That’s why scientists have developed a range of chemicals intended to kill or repel such insects, many of which are called pyrethroids, which target the mosquito’s central nervous system. In the study, now published, researchers found evidence of mosquitoes in Vietnam and Cambodia. They have evolved to be highly resistant to pyrethroids.
Scientists have collected mosquitoes in Vietnam, Indonesia, Ghana and Taiwan. Permethrin, a commonly used pyrethroid, was then sprayed in all areas where samples were collected. They discovered this Only 20% of mosquitoes collected in Vietnam died. Mosquito mortality rates in other samples were as expected.
The researchers then looked at the genomes of mosquitoes that survived the pesticide exposure and found a mutation in the L982W gene, a gene already linked to resistance in mosquitoes. The team then collected more samples, this time from Singapore and Cambodia, and examined their genes, looking specifically at the L982W gene. They found 10 unique species with mutations similar to those seen in Vietnamese mosquitoes, and nearly all of them were in Cambodia.
The researchers predicted Up to 78% of mosquitoes collected in Cambodia or Vietnam were resistant to pyrethroids, and those with the pyrethroid mutation were found to have an average 50 to 100-fold increase in resistance. They also looked for combinations of mutations that lead to this resistance and found that those with the combination of L982W and other mutations they can survive at pyrethroid exposure levels 500 to 1000 times higher than the amount that normally kills mosquitoes.
The researchers conclude that other countries should start conducting stress tests to determine the true extent of the problem.
Concern in Africa
Similar problems are being discovered in Africa. Scientists have discovered that a Which caused the malaria epidemic in Ethiopia this year Arrival in East Africa a type of mosquito (anofel stephensi) resistant to insecticides. This is a worrying finding, as it complicates efforts to eradicate the disease in Africa, where 95% of the world’s malaria infections occur. It also triggered the researchers’ concern, as the behavior of this species is different from that of other malaria carriers.
This a. stephensiCommon in South Asia, it may be behind recent fluctuations of malaria in East Africa. And data presented at the annual meeting of the American Society for Tropical Medicine and Hygiene on November 1 clearly show that this mosquito species is responsible for the outbreak in Dire Dawa, Ethiopia.
before you come a. stephensiMalaria infections were not common in Dire Dawa. But Cases, which were 205 in 2019, have skyrocketed to over 2,400 so far in 2022. Mosquito that can pick up malaria parasites from the blood of an infected person and pass it on to others nearby.
To identify the exact species, the researchers searched their breeding sites and collected adult mosquitoes around the homes of those involved in the study. About 97% of adult mosquitoes collected a. stephensiand the researchers found more breeding grounds around the homes of people who tested positive for malaria.
Reference work: https://www.science.org/doi/10.1126/sciadv.abq7345
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Source: Informacion
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