New dengue strain detected in Brazil could increase severe cases

A new strain of dengue has been detected in Brazil, which is currently dealing with an epidemic of the disease, which can be worrying because a second infection with a new strain can have more serious effects, explained an expert.

“The situation in Brazil is an epidemiologically complicated situation, that is, the emergence of new variants is potentially complicated because the subsequent exposure to different serotypes presents an increased risk that these infections progress to more serious situations of from a clinical point of view,” he added. virologist Ricardo Parreira, from the Institute of Hygiene and Tropical Medicine (IHMT), told Lusa.

The specialist spoke with Lusa about the news of the detection, by researchers from the Osvaldo Cruz Foundation (Fiocruz), in Brazil, of the first case of genotype 2 of dengue virus serotype 2, also known as of cosmopolitan genotype.

Although it is the most common genotype in the world, currently circulating in Asia, the Middle East and the Pacific, it had never been detected in Brazil and only reached the Americas in 2019. when it was detected in Peru, write the researchers in their article, published in April on the medRxiv platform before being peer-reviewed.

According to the article, the identification was made in February in a sample of a case that occurred at the end of November in the city of Goiás, precisely the region most affected by the current epidemic in Brazil, with an incidence of 1,714 cases per 100,000 population. inhabitants, and 380% more cases than last year.

Despite the number of cases in Goiás, Fiocruz scientists stress that they cannot establish a direct relationship between the new genotype and the increase in infections.

However, Ricardo Parreira recalled that researchers from the Brazilian foundation have identified an increase in more serious cases and concluded that it is “probable that the emergence of this new strain could generate an increase in these more serious cases”.

For the researcher, the appearance of a new strain of dengue fever is not surprising, especially as international travel resumes after the pandemic period, but “the arrival of a certain novelty in any territory where already circulating other strains of dengue virus. “is always a sign of concern”.

Brazil is a country in which a large part of the population has already been infected with this virus, and “the entry of a new variant into a population that ‘a priori’ may already have, for the most part, been infected with another variant may increase the risk that, from a clinical point of view, things will evolve into a more serious situation”.

In severe cases, dengue fever can progress to what is “mildly misused” called dengue hemorrhagic fever, he explained.

“It’s not always hemorrhagic. But it’s always associated with disturbances in the circulatory system, with an increase in the permeability of the capillaries, and it can evolve into shock situations and, ultimately, death. “, he added. added.

According to the latest epidemiological bulletin from the Brazilian Ministry of Health, published on Friday, dengue fever cases in Brazil increased by 151.4% in the first four months of 2022 compared to the same period of the previous year, and already exceed the total number of diagnoses for 2021.

The data shows that, through April, 757,068 probable dengue fever cases have been recorded in the country, while in the 12 months of 2021 together, only 534,743 have been identified.

“In Brazil, they are currently experiencing a considerable spike in dengue fever. Therefore, a greater number of infections implies a greater number of people infected secondarily, after having already been infected at some point, and this will inevitably increase the most cases. more serious. (…) It seems that the two things are linked”, defended Ricardo Parreira.

Dengue fever is a viral infection transmitted to humans by the bite of an infected mosquito.

There are four serotypes of dengue virus and contact with just one of them creates immunity against that serotype, so it is possible to catch the disease four times, according to the World Health Organization (WHO).

There is no specific treatment for dengue or severe dengue, but early detection and access to medical care reduce the case fatality rate to less than 1%.

The incidence of the disease has increased dramatically and approximately half of the world’s population is currently at risk.

An estimated 100 to 400 million cases occur each year, but more than 80% are mild or asymptomatic, according to the WHO.

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