Dengue serotype 3 has shown a notable increase in positive dengue test results in Brazil, particularly in the states of São Paulo, Minas Gerais, Amapá, and Paraná. This rise, observed primarily during the last four weeks of December, has raised concerns among health authorities, as this virus has not been the predominant circulating strain in the country since 2008, leaving a significant portion of the population susceptible to infection.
Data from the Ministry of Health indicate that in 2024, dengue serotype 1 was the dominant strain in Brazil, accounting for 73.4% of positive samples. A significant shift towards serotype 3 is now being observed.
Projections from the Ministry of Health, based on patterns recorded in 2023 and 2024, suggest that most dengue cases in 2025 will be concentrated in the states of São Paulo, Rio de Janeiro, Espírito Santo, Tocantins, Mato Grosso do Sul, and Paraná, where incidence rates are expected to surpass those of the previous year.
In 2025, Brazil will remain under the influence of El Niño, which brings high temperatures and thermal extremes. Additionally, the ongoing drought is leading people to store water, often under inadequate conditions, further facilitating mosquito proliferation.
