Thursday , July 29 2021

Dengue's Near Risk in Brazil: How Does Aedes Aegypti Mosquito Behave?



There is a high probability of dengue breakout 500 Brazilian cities and 1,880 municipalities are on standby, As shown by the system's data for a rapid survey of infection rate by Aedes aegypti. (LIRAA). It is the mosquito responsible for transferring two dengue, Zika and chikungunya as well, yellow fever in urban contexts. According to recent data from the LIRAA, which analyzes the percentage of households that may be the epicenter of mosquito spread, cities such as Rio de Janeiro and Nero or Brasilia are among the major capitals on alert for dengue epidemics. This is a recurring situation whenever the summer season, which lasts from December to March, comes.

Dengue is a disease caused by the spread of a virus present mainly in areas of tropical and subtropical climate. To date, there is no treatment against the disease and the main purpose of prevention is to develop effective vaccines against the four serotypes or strains of the dengue virus, according to the World Health Organization (WHO). Today, Dengvaxia ® (CYD-TDV) vaccines, created by the Sanofi Pasteur laboratories, and others such as the one developed by the Botanic Institute in Brazil, which has recently been sold to the United States, Merck Sharp and Dohme (MSD), have been commercialized. , Or the Institute of Bio-Manguinhos of the Oswaldo Cruz Foundation (Fiocruz) in collaboration with the pharmaceutical company GlaxoSmithKline (GSK).

Pyukroz is a biomedical and environmental research institution based in Rio de Janeiro since 1900, representing one of the main beneficiaries of research against the spread of dengue worldwide. Rappella Bruno, head of the Molecular Insect Laboratory at the Oswaldo Cruz Institute (IOC), one of the oldest sections of the Pocruz, is investigating the behavioral changes of the mosquito Aedes aegypti. Once infected with a virus, especially dengue or affinity. This biologist explains, in an interview with RT, the current risks of the dengue epidemic, and the characteristic behavior of the mosquito transmitted.

RT: In the current Brazilian context, what is the risk of developing a dengue epidemic?

& # 39; B & # 39 ;: Once in the summer, the risk of epidemics is always close. This is because the rise in rainfall and high temperatures, which are characteristic of this season, are an excellent combination for the spread of mosquitoes.

"Aedes aegypti" to develop better and faster with high temperatures. your Eggs can resist up to a year In a dry environment, and with the arrival of a humider and warmer climate, the eggs end up developing and yielding new mosquitoes "Aedes aegypti", dengue and zygene transmitters, among others.

RT: How does the growth of mosquitoes affect the spread of this virus?

& # 39; B & # 39 ;: "Aedes aegypti" is so far the only known transmitter of Dengi. The more mosquitoes of this type, the more likely they will bite an infected person and transmit the virus to another person.

Raphael Bruno, director of the molecular insect laboratory of the Oswaldo Cruz Institute.

"Dengue continues to be one of the most dangerous viruses that is present throughout the year and in summer the incidence is higher, but infection can occur at any time of the year."

Raphael Bruno, director of the molecular insect laboratory of the Oswaldo Cruz Institute.

That mosquito Prefer to feed on human blood, So transmission is usually transmitted from one person to another and this specific mosquito as a carrier. However, the virus is transmitted only when it is in the replicator stage of the person, that is, with the developed disease.

RT: What is the main risk at this stage?

& # 39; B & # 39 ;: Today the biggest fear is the chikungunya virus, also transmitted by Aedes aegypti. So far there have been no strong outbreaks but this year there have been a number of cases of higher chikungunya than in previous years. Some groups are looking to know Why during a certain period a virus stops rotating or gives room to others, But we do not know the specific reasons so far.

Beyond the specific concern with chikungunya, dengue continues to be one of the most dangerous viruses that is present throughout the year. In the summer the prevalence is higher, but the infection can occur at any time of the year because of the four existing serotypes, always possible to circulate in any area of ​​the country.

RT: Where does the cycle begin?

& # 39; B & # 39 ;: It goes back a long time. These infection cycles began in cows' environments, where viruses were passed on by other insects and then blinded. "Aedes aegypti" Participates only in the urban cycle, Where these viruses have been fully installed, especially Dengue.

RT: How did these viruses go from the desert to the urban areas?

& # 39; B & # 39 ;: Dengue, Affinity, Chikungonia, or Yellow Fever were viruses found in monkeys, but spread as a result of human presence in nature. How do people first get it? It varies and inaccurate data Because it depends a lot on the place.

With yellow fever we know that transmission in the wild zone occurs through mosquitoes of "Sabethes" or "horticulture", but for the wild transmission of dengue, affinity or chikungunya viruses we do not have such precise discoveries. Already in the urban context, all of these viruses are being passed by Aedes aegypti. .

RT: One of the main goals of your research group is the behavior analysis of Aedes aegypti. What are the main manifestations of studies?

& # 39; B & # 39 ;: When a mosquito "Aedes aegypti" carries the dengue usually has a shorter life time, it places fewer eggs but becomes more active and increases its ability to move. On the contrary, the mosquito contract afflicts the virus and becomes slower, less moving but puts the same eggs and the mosquito is not infected. In addition, the lower displacement capacity of the afflicted mosquito explains why so many cases of infection occur in the same family, as the mosquito tends to seek food within a small radius of distance.

RT: What is the life cycle of the mosquito? Aedes aegypti & # 39; And what are the mutation options observed in your study?

& # 39; B & # 39 ;: Their lifespan varies from 15 to 20 days in a natural environment, and mosquitoes bred in the laboratory reach up to 45 days. The mutations that occur in these mosquitoes are of natural origin and it takes a long time until some relevant effect occurs. In nature there are different populations of mosquitoes that can be more or less susceptible to viruses according to a phenomenon we call "Vector Vector Interaction".

Raphael Bruno, director of the molecular insect laboratory of the Oswaldo Cruz Institute.

"The most effective thing is to avoid places that are easy to copy" Aedes aegypti, "that is, to prevent stagnant water where a mosquito can lay its eggs, these eggs are almost invisible to the human eye.

Raphael Bruno, director of the molecular insect laboratory of the Oswaldo Cruz Institute.

That is, sometimes the genotype of the mosquito can not be compatible with the genotype of the virus. Depending on the region of Brazil, there are different populations of mosquitoes, as a result of various selective pressures of the environment. In our genetic analyzes, we notice that the population of a particular area may be more sensitive to the swine virus than another, and therefore the incidence of infection from one area to another varies.

RT: The level of the dengue epidemic is a more current risk factor known in Brazil, while chikungunya is old but less frequent and Zika is recently, though threatening. What are the variations in the frequency of these three viruses transmitted by the same mosquito?

& # 39; B & # 39 ;: Dangy represents a more dangerous creature that has four serotypes that can cause it: Dengue 1, Dengue 2, Dangy 3 and Dengue 4. That is, those who already had a serotype immunized against it specific, but if another serotype starts to turn around the person will again be exposed to Dengue. In the case of Zika and Chikungunya there is only one sorotype, therefore, after the infected person is immune to eternity.

RT: What was the cause of an affinity outbreak that Brazil began to live about three years ago?

& # 39; B & # 39 ;: The introduction of rapport in the country was recently. In 2015, the first cases began to be recalled, mainly in the northwestern part of the country, but the first suspicions that it was found were found only in October of that year, after microscopic cases in babies of mothers infected with the virus. There is a hypothesis that thinks the virus has come During the Confederation Cup; Another notes that he came during the championship rowing with many competitors from France and Polynesia, where one of the first blows occurred. When Zika arrived in Brazil, no one was protected, so it caused great destruction. It spread very quickly and many people were infected, but today the tendency is for a number of cases to come down because many people have been vaccinated.

RT: Based on your research, what are the mechanisms to combat this mosquito species and prevent infections?

& # 39; B & # 39 ;: The most effective is to prevent places that help reproduction of Aedes aegypti, that is, to prevent stagnant water where a mosquito can lay its eggs. Those eggs Almost invisible to the human eye In addition, females tend to place them in dark places. Therefore, avoiding places that help incubation of eggs, from a plate of pot to the lid of a soda bottle, is the most effective.

RT: How does Brazilian public power participate in preventing a dengue epidemic?

& # 39; B & # 39 ;: It is a joint work of research and information on the forms of breeding of the mosquito to prevent it from reproducing. Although public authorities are responsible for basic sanitation and garbage collection, this mosquito only reproduces in clean water. There are mosquito courts that take place inside people's homes, and from there, every mosquito gets moving within a radius of about 300 meters. so, Prevention is a shared responsibility, Of the public forces, of the research institutions and of the inhabitants of the cities, is currently focused on dengue epidemics.

RT: Following these methods, would you be able to eradicate the dengue virus?

& # 39; B & # 39 ;: In the short term, at least, no. By working together and collectively, we can significantly reduce the mosquito population, which is the only way to reduce the spread of the virus.

In addition to the information strategy of the population, there is a complementary method of combat that includes the release of modified mosquitoes. This can be done with transgenic male mosquitoes that when crossed with wild females to give birth to offspring that dies, that fails to live. The other technique is to release mosquitoes that contain a bacterium called the Volbecia. Which prevents the virus from multiplying within it.

Luna Gomez

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