Asian mosquito threatens African cities

Tuesday September 15, 2020 / an Asian mosquito threatens African cities

While the disease is now concentrated in rural areas of the continent, a new, expanding species is colonizing urban areas.

Tens of millions of inhabitants of African cities are threatened by a malaria vector mosquito native to Asia and particularly adapted to the urban environment, warns a study published Monday, September 14. Malaria is a disease triggered by a parasite (Plasmodium falciparum or vivax) transmitted mainly by around forty species of mosquitoes. About 400,000 people died in 2018, mostly children, especially in Africa.

On this continent, one of the main mosquitoes is Anopheles gambiae, considered the most dangerous animal on Earth, but it does not like polluted puddles in cities and has not learned to lay its larvae. in urban clean water reservoirs. In Africa, malaria is now concentrated in rural areas.

In her study published by the American scientific journal PNAS, medical entomologist Marianne Sinka, a researcher at the University of Oxford, maps the expansion of another species, the Anopheles stephensi, native to Asia, and which, she has learned to exploit the water reservoirs of cities (especially those made of cement and bricks), where she sneaks through any hole to deposit her larvae. “It is the only species to have succeeded in penetrating central urban areas,” the scientist told AFP. Stephensi caused the first outbreak in Djibouti in 2012, a city where malaria hardly existed, and has since been observed in Ethiopia, Sudan and elsewhere.

Remove any standing water

Marianne Sinka used a model to predict the places in Africa where the environment was most suitable for the introduction of this imported mosquito: places with high density, where it is hot, and of course with sufficient rainfall. The study concludes that 44 cities are “highly adapted” to the insect and that 126 million Africans who are spared today are at risk, mainly in the equatorial region. “The 40% of people who live in urban areas could suddenly be vulnerable and infected with malaria, it would be very serious”, warns the researcher.

How to protect yourself from it? Unlike African mosquitoes, which like to bite humans when it is cooler – so at night – bed nets would be less effective, she said, because stephensi likes to bite in the evening, when it is still hot. Better to install mosquito nets on the windows, soak the walls with insecticides and cover your body. But the most essential measure is to target the larvae and thus remove any stagnant water, as well as to close any water reservoir tightly. This is what worked in India, recalls Ms. Sinka.

The World with AFP

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