MercoPress. South Atlantic News Agency

Presence of serotype 3 of dengue virus worries Brazilian authorities

In the last four weeks of 2024, 84% of dengue cases were mainly in São Paulo, Espírito Santo, Minas Gerais, Paraná, Goiás, and Santa Catarina

Brazilian health authorities have expressed concern following the reappearance of the dengue virus serotype 3, particularly in the states of São Paulo, Minas Gerais, Amapá, and Paraná since the last four weeks of December, Agência Brasil reported Thursday. The virus has not circulated predominantly in the country since 2008. According to the Pan American Health Organization (PAHO), the disease generated a “historic epidemic in the Americas” in 2024, with more than 12.6 million cases.

As per the Brazilian Health Ministry, the predominant variant in 2024 was version 1, found in 73.4% of the samples testing positive for the disease. “We're seeing a significant shift towards serotype 3,” Health Surveillance Secretary Ethel Maciel said Thursday. “I want to draw attention to the fact that serotype 3 has not circulated in Brazil since 2008. We've had 17 years without this serotype circulating in greater numbers. So we have a lot of susceptible people, who haven't come into contact with this serotype and could have the disease. This is a variable that we are putting into our COE [Emergency Operations Center] to monitor the circulation of these viruses.”

A projection based on the patterns recorded in 2023 and 2024 in Brazil and presented by the Ministry reveals that most of the dengue cases expected in 2025 should be recorded in the following states: São Paulo, Rio de Janeiro, Espírito Santo, Tocantins, Mato Grosso do Sul and Paraná. In these locations, the incidence is expected to be higher than last year.

“What can we expect for 2025? We continue to have the El Niño effect and, therefore, high temperatures and these temperature extremes. We also have the problem of drought, which causes people to store water, often in inappropriate places. And this also leads to the proliferation of mosquitoes,” she added.

She also pointed out that “the increase in the circulation of serotype 3 was not included in this modeling,” and she reckoned that “we don't know how it will spread; we are monitoring it.” In the last four weeks of 2024, 84% of dengue cases were concentrated in the states of São Paulo, Espírito Santo, Minas Gerais, Paraná, Goiás and Santa Catarina.

Data from the ministry also shows that, in the last four weeks of 2024, 82% of all probable Zika cases identified in the country were concentrated in Espírito Santo, Tocantins, and Acre. In addition, 3,563 probable cases of Chikungunya were identified in the last four weeks of December, 76.3% of them in São Paulo, Minas Gerais, Mato Grosso, Espírito Santo, and Mato Grosso do Sul. “The states are repeating themselves, some for dengue, Zika, and Chikungunya,” Maciel admitted.

Also Thursday, the Adolfo Lutz Institute confirmed that the viral outbreak affecting several cities on the southern coast of São Paulo was caused by norovirus. Noroviruses are a group of viral diseases known as gastroenteritis and are usually transmitted via the fecal-oral route. According to the São Paulo State Health Department, norovirus is an illness that lasts an average of three days, causing symptoms such as nausea, vomiting, diarrhea, abdominal pain and sometimes muscle pain, tiredness, headache, and low fever.

Tourists in São Paulo coastal resorts have been complaining about the increase in cases of malaise. The Guarujá City Hall even declared an outbreak of gastrointestinal viruses with frequent and liquid evacuations, difficulty hydrating with vomiting, dry skin and mouth, and difficulty urinating. Treatment consists mainly of hydration, even intravenously in the most complicated cases.

In this scenario, the Government of Argentina issued Thursday a series of recommendations for nationals traveling to one or more of the 33 countries with a presence of dengue, such as Brazil, Colombia, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, and Panama.

“Prevention measures consist of applying repellent frequently following the instructions on the package, especially in the early morning and at dusk, when the Aedes aegypti is most active,” Buenos Aires stated while noting that “timely and adequate treatment reduces the probability of experiencing severe forms of the disease.”

Meanwhile, the Argentine province of Misiones, which borders Brazil and Paraguay, celebrated the low occurrence of dengue. Provincial Epidemiology Director Eduardo Ramírez noted that the strategies implemented proved effective.

“As every year, we continue to be aligned with the strategic plan for the integrated management of vector-borne pathologies; this includes the registration and communication of cases, the promotion of behavioral changes in the population, and constant monitoring at the provincial level,” he stressed. He also highlighted the low number of confirmed dengue cases after 482 suspected ones came out negative. “The people who did test positive have already gone through the febrile period and are in full recovery. The epidemiological curve of the disease remains stable, with no signs of a significant increase,” he said.