Dengue: a study shows the deviant behavior of mosquitoes carrying the virus

Scientific work has revealed that dengue-carrying mosquitoes lose part of their reason. Therefore, the insect would be subject to the virus, which would increase the risk of transmission to humans. explanations.

Surprising discovery. Carried out in collaboration between French and Singaporean researchers, the scientific work shows the change in behavior of Aedes aegypti, female mosquitoes that feed on humans. When they are infected with the dengue virus, they are stunned, as if they were “manipulated” by the virus, and they lose part of their reason.

Strongly present overseas, particularly in Réunion and the West Indies, Dengue virus causes 400 million infections and 25,000 deaths each year, according to the Institute for Research and Development (IRD). Julien Pompon, a researcher at the MIVEGEC laboratory in Montpellier, supervised and coordinated this three-year study on the behavior of mosquitoes. The scientist noticed that the actions of the Aedes aegypti were particular when previously infected: “We also know that mosquitoes that transmit malaria have changed behavior once infected. We asked ourselves the question for the dengue virus, do infected mosquitoes have a changing behavior?

The study was conducted on one hundred mosquitoes, half of which were infected with dengue. “We built small cages in which we put a mosquito with a sleeping mouse. Using a high-definition camera we were able to precisely observe their behavior, from which we obtain an overview”explains Julien Pompon.

the Aedes aegypti become “distressed,” according to the scientist. “It has been observed that infected mosquitoes are more attracted to mice, which means that these mosquitoes will get closer to a human host to bite them more. Second observation, infected mosquitoes need to bite several times to extract the same amount of blood. as uninfected mosquitoes.

With every bite from an infected mosquito, even a short one, there will be dengue transmission.

Julien Pompon, MIGEVEC researcher

In this case, dengue virus transmission would be three times higher than normal. “It’s exponential”, adds Julien Pompon. “Finding that the number of bites increases with mosquito infection was not obvious, that’s the discovery. The evolution game caused the virus to mutate to change the behavior of the mosquito in order to optimize its transmission.

The explanation is that the mosquito does not arrive “on blood food”Julien Pompon explains: “Infected mosquitoes bite, but they don’t go to the vein, they don’t find it. The infection changes the sensory organs of the mosquito or weakens it.”

According to a study carried out in China, a derivative of vitamin A could attenuate the proliferation of a bacterium present in dengue fever in humans. This derivative, called isotretinoid, has already been tested in mice and the results have been conclusive.

For the MIGEVEC scientist, this may be a solution to counteract the proliferation of dengue: “Why not? Vitamin A is not toxic at too high a dose. We need to do human clinical trials first.”

And precisely, the tests are scheduled for this fall, in Malaysia.

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