Mosquitoes, responsible for the transmission of dengue fever and other diseases, have developed resistance to insecticides in parts of Asia.
Mosquitoes that transmit dengue fever and other sometimes serious viral diseases have developed high resistance to insecticides in parts of Asia and new methods are urgently needed to stem their spread, according to a recently published Japanese study.
Spraying insecticides in mosquito-infested areas is a common practice in tropical and subtropical regions. Resistance was already a concern, but until now the exact extent of the problem was unknown.
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Gene mutations
Japanese scientist Shinji Kasai and his team studied mosquitoes from several Asian countries and Ghana and found genetic mutations that make some of them immune to widely used insecticides such as permethrin.
This director of the medical entomology department at Japan’s National Institute of Infectious Diseases found that some types of mosquitoes that should have been 100% eliminated by insecticides were now only 7%. And even a ten times higher toxic dose only killed 30%.
Resistance levels vary by region. For example, according to Shinji Kasai, they “differ totally” between Cambodia and Vietnam. His work also revealed that in Ghana, parts of Indonesia and Taiwan, existing insecticides still worked for the time being.
New chemicals
This study published in late December by the journal ‘Science Advances’ shows that ‘commonly employed strategies may no longer be effective’ in controlling ‘harmful mosquito populations’, according to University of Sydney expert Professor Cameron Webb who was interviewed. of the AFP.
New chemicals are needed, but authorities and scientists also need to consider new methods of protection, such as vaccines, according to Cameron Webb. There are currently only a few dengue vaccines available – Japanese pharmaceutical group Takeda’s was approved last year by Indonesia and then by the European Union, while French Sanofi’s use is very limited because it can aggravate the disease in people who have never had this virus before.
The alternatives are to step up efforts to eliminate mosquito breeding grounds or to sterilize male mosquitoes using Wolbachia bacteria, an innovative method that has already produced encouraging results locally.
