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Dengue is a deadly disease that often spreads in densely populated areas. Scientists have come up with different ways to deal with it, but it turned out that sometimes one cannot do without volunteers on the ground, and in some areas a stranger, even a doctor, can simply be killed. “Medusa” with some additions retells article New Scientist publications on how dengue is being tackled in Brazilian slums using two ingenious approaches.
How mosquitoes are turning from carriers of infection into weapons of biocontrol
Dengue is viral infectionthat is spread by mosquitoes some types in many regions, but most affects Southeast, South Asia and the American continent (except Canada and Chile). But, perhaps, due to global warming, dengue will spread to non-typical countries like Great Britain.
In year falls ill between 100 and 400 million people. Dengue usually causes no symptoms or only a fever. But if the disease took severe forms (this happens in 5% of cases), then the forecast the best thing in cases where a person immediately seeks medical help, otherwise in one case out of five everything will end in death.
Although there are different ways to combat the spread of dengueevery year it gets sick More human. Therefore, scientists come up with more and more promising ways. One of them is the spread among mosquito-carriers of a special strain of bacteria of the genusWolbachia, representatives of which infect many types of insects.
Wolbachia of this special strain make mosquitoes practically resistant to dengue infection, that is, mosquitoes cease to be dangerous to humans. At the same time, Wolbachia spread very quickly in the insect population – due to the fact that all offspring after mating mosquitoes, one of which is infected with a bacterium, turns out to be a carrier of the bacterium.
All this allows you to use the technique to fight dengue. biological control — in different countries began to launch programs in which mosquitoes infected with Wolbachia are released in dengue areas.
“Heroes against dengue” as agents of doctors in the favelas
In Brazil, such a program was supported by the Ministry of Health. However, during its implementation, it became clear that in the favelas of Rio de Janeiro, mosquitoes resistant to infection are difficult to spread. Favelas are slums in which tens or even hundreds of thousands of people live in close quarters. Enter there for a stranger dangerous – gangs set their own rules there and can rob or kill without much consequences for themselves.
At first, specialists tried to launch mosquitoes from the territory of schools and hospitals, but nothing came of it, since these institutions are usually located on the outskirts of favelas. They also cannot spread independently throughout the area – almost all mosquitoes, including dengue carriers, fly very close from the place of laying eggs – within a few hundred meters. They even tried to blow mosquitoes into inaccessible areas using a long pipe. But that didn’t help either. The campaign became successful only when children were involved in it.
Since 2014, the Heroes Against Dengue project has been running in the favelas. It was created by the German physician Norbert Lehmann. In 2005, he came to a poor area of Rio de Janeiro to deliver equipment and provide all possible medical assistance. There, the medic encountered the death of a local child from dengue, which made a great impression on him. Returning to Germany, Lehmann raised money and created the Heroes Against Dengue project.
The essence of the project is that children who can move freely around the favelas were taught basic knowledge about dengue: what symptoms should definitely see a doctor, how to reduce the risk of getting sick (for example, you need to get rid of stagnant water – mosquito larvae develop there). Volunteers went (and go) from house to house and told this to the people who live in the favelas. For children, this is an important thing that they are proud of.
Norbert Lehmann came up with the idea of the project based on his own experience. When he played football with his friends in the Rhine as a child, there were also a lot of mosquitoes. Children told their parents about places where the situation is the worst.
They passed information to the authorities, and the authorities sent helicopters from which crushed ice with Bacillus thuringiensis israelensis bacteria was dropped. Their distribution was supposed to render mosquitoes infertile and was previously considered as one of the alternative methods of biological control of dengue (although not very successful).
When Lehmann learned in 2019 of the failure of the mosquito Wolbachia in the favelas, he offered the help of hundreds of volunteers from Heroes Against Dengue. Now these teenagers grow mosquitoes at home and at a certain stage leave them in different places in the Complexo da Maré – association 16 favelaswhere lives 130 thousand people.
AT research shownthat the spread of mosquitoes with Wolbachia is an effective measure in the fight against dengue. However, it is still difficult to say how effective the involvement of child volunteers in the favelas is (although common sense suggests that it is most likely quite effective). Moreover, it is quite difficult to obtain data on incidence from these areas.
Similar programs have already been launched in other favelas of Rio de Janeiro and are being considered as a possible option in other cities in Brazil, where there are also problems with the spread of mosquitoes in the favelas.