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New dengue strain detected in Brazil may increase severe cases

A new strain of dengue has been detected in Brazil, which is currently facing an outbreak 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 subsequent exposure to different serotypes has an increased risk that these infections will evolve into more serious situations from a clinical point of view,” he said. Virologist Ricardo Parreira, from the Institute of Hygiene and Tropical Medicine (IHMT), told Lusa.

The specialist spoke to Lusa about the news of the detection, by researchers of the Osvaldo Cruz Foundation (Fiocruz), in Brazil, of the first case of genotype 2 of serotype 2 of the dengue virus, also known as 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 had only reached the Americas in 2019, when it was detected in Peru, the researchers write 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 ongoing outbreak in Brazil, with an incidence of 1,714 cases per 100,000 inhabitants, and 380% more cases than last year.

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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 identified an increase in more serious cases and concluded that it is “likely that the emergence of this new strain may be generating an increase in these more serious cases”.

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

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

In severe cases, dengue can develop into what, “in a slightly abusive way”, is called hemorrhagic dengue, he explained.

“It is not always hemorrhagic. But it is always associated with disturbances at the level of the circulatory system, with an increase in the permeability of the capillaries, and this can evolve into situations of shock and, at the limit, death”, he added.

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

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The data show that, until April, 757,068 probable cases of dengue were registered in the country, while in the 12 months of 2021 together, only 534,743 were identified.

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

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

There are four serotypes of the dengue virus and contact with only one of them creates immunity to 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 fatality rate to below 1%.

The incidence of the disease has grown dramatically and about 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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