Brazil is the nation most affected by dengue within the Americas. Credit score: Marcelo Camargo/Agência Brasil
The reemergence of dengue virus serotype 3 (DENV-3) in Brazil after 17 years may assist worsen contemporary outbreaks of the illness there, because the inhabitants isn’t immunized in opposition to this serotype, and serotypes 1 and a pair of (DENV-1 and DENV-2) proceed to flow into.
The warning options in an article written by researchers on the São José do Rio Preto Medical College (FAMERP) in São Paulo state, and revealed within the Journal of Medical Virology.
“The last significant DENV-3 epidemic in Brazil, and more specifically in São José do Rio Preto, occurred more than 15 years ago [in 2007]. DENV-1 and DENV-2 are continuously circulating in Brazil. If DENV-3 establishes itself again and the situation persists [with these serotypes co-circulating], severe forms of dengue epidemic could result. This is precisely the situation we’re experiencing right now in São José do Rio Preto,” Maurício Lacerda Nogueira, a professor at FAMERP and final creator of the article, informed Agência FAPESP.
For 20 years, Nogueira and colleagues have performed a Thematic Venture that features genomic and epidemiological surveillance of dengue and different illnesses brought on by insect-born viruses (arboviruses) in São José do Rio Preto, the place dengue has been endemic for a number of many years, with a succession of outbreaks brought on by totally different serotypes.
“The annual average temperature in São José do Rio Preto is about 25 °C , and rainfall averages about 2,000 millimeters per year. This warm wet weather creates ideal conditions for the mosquitos that transmit arboviruses to breed and makes the city a suitable place for genomic and epidemiological monitoring of arboviruses, including dengue. We’ve been doing this for a long time, so we’re able to make reliable epidemiological inferences,” Lacerda mentioned.
The researchers have documented an increase in circumstances of the illness brought on by DENV-3 within the metropolis since late 2023 by way of lively surveillance of arboviruses in sufferers with dengue-like signs handled at Hospital de Base and UPAs (public clinics specializing in medium-complexity circumstances).
Thirty-one blood samples collected between November 2023 and November 2024 examined optimistic for DENV-3. The most typical signs have been muscle ache, headache, and fever.
“In 2023-24, we had a dengue epidemic in São José do Rio Preto, caused mainly by DENV-1 and -2. In mid-2024, DENV-1 almost disappeared, and DENV-2 became the main agent. The number of DENV-3 cases then began to rise, and it’s now the main agent in the city,” Lacerda mentioned.
Research performed by different teams present that the final outbreak of dengue in Brazil, in 2021, was brought on by DENV-1, and that sequential an infection by DENV-3 is related to elevated severity throughout epidemics.
“However, we didn’t observe increased severity in the patients who participated in our study,” Lacerda mentioned.
Want for lively surveillance
The researchers additionally sequenced the genomes and analyzed the phylogenies of the viral isolates collected from the blood samples donated by sufferers with acute fever. The outcomes of the evaluation confirmed that the DENV-3 pressure in query belonged to the identical lineage because the one recognized in Florida (U.S.) and the Caribbean, and differed from the strains of DENV-3 that circulated in Brazil within the 2000s.
These findings counsel that the outbreak of DENV-3 in Florida and the Caribbean in 2022–24 most likely contributed to the introduction of the virus to Brazil and its unfold all through the nation, in line with the researchers.
“This demonstrates the extent to which molecular and genomic surveillance of circulating DENV strains is crucial to public health preparedness efforts and the response to the surge in cases of the disease,” Lacerda mentioned.
Dengue transmission is widespread throughout tropical and subtropical areas worldwide. Nonetheless, at-risk areas have expanded in previous many years, owing primarily to local weather change and an elevated vary of Aedes aegypti, the mosquito that transmits the virus, the article notes.
Brazil is probably the most affected nation within the Americas and has lengthy been hyperendemic for all dengue virus serotypes. In recent times, DENV-1 and -2 have been the commonest serotypes in circulation. Though DENV-3 was detected throughout the interval mentioned within the article, the variety of circumstances was very small. In reality, fewer than 100 circumstances have been reported nationwide between 2010 and 2022. Nonetheless, the variety of circumstances reported elevated in 2023, reaching 106, and jumped to 1,008 in 2024.
“We’ve been studying dengue in Brazil since 2010, and the epidemiological pattern is similar to that observed for SARS-CoV-2 during the COVID-19 pandemic. When a different serotype emerges, it escapes the population’s established immunity, and an epidemic occurs shortly afterward. We’re seeing this now with DENV-3,” Lacerda mentioned.
Extra data:
Lívia Sacchetto et al, Early insights of dengue virus serotype 3 (DENV-3) re-emergence in São Paulo, Brazil, Journal of Medical Virology (2025). DOI: 10.1016/j.jcv.2025.105763
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Reemergence of dengue serotype 3 could enhance severity of outbreaks of the illness in Brazil (2025, February 12)
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