Published on : 18/05/2022 – 04:48
Malaria vector mosquitoes in Africa do not bite almost exclusively at night. A study conducted in Bangui, in the Central African Republic, indicates that 20 to 30% of bites take place during the day, well beyond what we thought. The means of combating malaria could thus be reviewed.
The study, published Tuesday May 17 in the scientific journal Proceedings of the National Academy of Sciences (PNAS), was conducted by researchers from the Pasteur Institute in Bangui and the Research Institute for Development in France. As always in research, everything starts with a question. Carlo Costantini is a medical entomologist, researcher at the Research Institute for Development. He is one of the authors of the study:
« Why, for several years, the incidence rate of malaria in Africa has stagnated? While with the distribution of mosquito nets impregnated with insecticide (to protect against mosquitoes at night while sleeping, editor’s note), there was at the beginning a rather spectacular fall in the incidence of malaria? This one stopped. »
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The researchers’ hypothesis is that mosquito behavior could be one of the causes. To decipher the habits and customs of these insects in terms of bites, they organized a rather special collection of mosquitoes in Bangui, for a year, two days a month: captures on men, volunteers, day and night.
« Each time a mosquito landed on the skin, the volunteer used a tube in which he captured the mosquito, so that it was known at what time that mosquito had tried to bite him. To our great surprise, a third of the bites took place throughout the day, during daylight hours and especially inside houses, when no one considered this window of time as a possible window for malaria transmission. »
So, have mosquitoes changed their behavior to counter the weapons used against them at night for 15 years? Or have they always acted this way in Bangui? Impossible to conclude. In any case, if the results of this study are confirmed elsewhere, the spraying of long-lasting insecticide on the walls of schools for example, and not only in homes, could be useful, suggest the researchers.
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