Infectious diseases: Brazil in dengue fever | nd-aktuell.de

Raissa de Souza Vieira marches up a steep street, motorcycles rattle past, the sun burns in the sky. Suddenly she stops and points to a puddle. “A perfect nest for mosquitoes.” Vieria, 25, with braces and pigtails, takes a photo with her smartphone. She says she will report the job to the city administration. The lively woman is a health agent in a favela in Niterói, a neighboring city to Rio de Janeiro. As in the rest of the country, we are currently fighting a powerful enemy here: dengue fever.

More infections than ever before

Many Latin American countries are experiencing outbreaks of the disease, which is transmitted by the Egyptian tiger mosquito (Aedes aegypti). This is not born with the virus. However, when mosquitoes suck the blood of a sick person, the virus multiplies in their bodies and is transmitted to the next person with a bite. The disease can quickly get out of control – as is now the case in Brazil. The country is reporting more infections this year than ever before. Many states have declared states of emergency.

In February 2019, Vieira suddenly felt very weak. She went to the doctor and was diagnosed with dengue. “It was terrible,” she remembers. “I could hardly move.” Many infected people report severe pain. That’s why the disease also has the telling nickname “bone crusher fever” in German. In addition to a high fever, infected people suffer from vomiting, muscle and joint pain, and an itchy rash. In rare cases – and especially in the case of multiple infections – the disease can lead to bleeding, which can be fatal.

Vaccination campaign and prevention

Brazil has now purchased 5.2 million doses of the dengue vaccine Qdenga, developed by Japanese drugmaker Takeda. The country received a further 1.32 million doses free of charge. A vaccination campaign started at the end of the year. The country has a long tradition of vaccination and a well-functioning public health system. Nevertheless, the vaccination campaign will hardly be able to slow down the current outbreak, also because children and young people are being given the injections as a priority for the time being.

The population is being called on everywhere to protect themselves, in TV commercials, on billboards, with loudspeaker trucks. Health agent Vieira often goes door to door to educate residents about prevention options. Her tip: Pour sand into the saucers of flower pots so that water doesn’t collect there. Mosquitoes prefer to lay their eggs in stagnant water. »And of course use mosquito spray.«

Before 1970, dengue was reported in only seven countries worldwide. Today, fever is the fastest spreading viral disease. There are eight times as many infections every year as there were 20 years ago. Even France and the USA registered cases of the tropical disease. Recently, the World Health Organization announced that half of the world’s population is at risk of infection. How can this be explained? “This is definitely related to the effects of climate change,” says Luciano Moreira “nd”. He is a researcher at the renowned Oswaldo Cruz Institute (Fiocruz). »For several years we have been observing rising temperatures on the one hand and more precipitation on the other. These are excellent conditions for mosquitoes.«

Outbreaks now also in the south

In recent months, the whole of Brazil has been suffering from an extreme heat wave. According to experts, in addition to climate change, the natural weather phenomenon El Niño is also responsible for this. It causes ocean currents and the climate to change. Parts of the eastern Pacific will be warmer, western parts will be cooler. “We are now also recording dengue outbreaks in the south of Brazil,” says Moreira. “The disease didn’t exist there before.”

Scientist Moreira was also involved in a project in which mosquitoes were infected in the laboratory with a bacterium called Wolbachia. This is intended to block the reproduction of the dengue virus in the mosquito. In initial experiments, dengue cases were drastically reduced where the infected mosquitoes called “Wolbitos” were exposed. The world’s largest mosquito farm will be put into operation in Brazil next year. But the Wolbachia project will not be able to stop the current outbreak because the test is limited to individual cities. That’s why Vieira will continue to walk through her favela over the next few weeks to find the mosquito breeding grounds.