In addition to claiming hundreds of thousands of victims every year worldwide, the mosquito is the animal that transmits the most diseases on the planet. In some humid regions of the world, this pest is now resistant to insecticides, which jeopardizes efforts to fight dengue fever, according to a Japanese study.
Mosquitoes are the vectors of many viral diseases, such as dengue, it’s cool, yellow fever, and Zikaor malariaone of the worst causes of death in the world, which affects more than 200 million people according to the World Health Organization (WHO). Dangerous mosquitoes are present in tropical areas throughout the year, and elsewhere in the world when it is sufficiently warm and humid. The mosquito Temples of the Egyptians for example, just like the tiger mosquito, terrorizing the planet. What particularly worries scientists is that in addition to maintaining dreadful epidemics like dengue throughout the world, it is able to resist insecticides, as certain bacteria resist antibiotics.
Temples of the Egyptians : “an extremely high level of resistance”
Japanese scientist Shinji Kasai and his team studied mosquitoes from several Asian countries and Ghana (West Africa), and found genetic mutations that immunize some against widely used insecticides such as permethrin, a substance contained in certain clothing repellents. “In Cambodia, more than 90% of Aedes aegypti mosquitoes – the main vector of dengue, Zika, chikungunya and yellow fever viruses – have a combination of mutations resulting in an extremely high level of resistance“, details the researcher for AFP. To reach this conclusion, the researchers evaluated the sensitivity of 23 populations of Aegypti, collected in Vietnam, Indonesia, Ghana and Thailand, to permethrin. They discovered that some types of mosquitoes that were supposed to be 100% killed by insecticides were only 7% killed. And even a toxic dose ten times higher only killed 30%.
What impact on the dengue fever control strategy?
On the other hand, the study published at the end of December by the magazine Science Advance suggests variable levels of resistance depending on the region. In Ghana, as well as parts of Indonesia and Taiwan, current insecticides still work for now. This essential work carried out by the department of medical entomology at the Japanese National Institute of Infectious Diseases shows that “commonly employed strategies may no longer be effective” in controlling populations of harmful mosquitoes, warns Professor Cameron Webb, a Sydney University expert interviewed by AFP. The first vaccine against dengue fever, “Qdenga” from the Japanese laboratory Takeda, has just recently received a favorable opinion from the European Medicines Agency for the marketing in Europe of its vaccine against this endemic disease in Asia, Latin America and in the West Indies. The WHO estimates between 100 and 400 million the number of cases diagnosed in the world, constantly increasing for twenty years. Shinji Kasai, for his part, fears that the super-resistant mosquitoes he has identified in Asia will spread elsewhere in the world “in the near future”, and particularly recommends to vary the insecticides more.
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