Brazil could reach 1.8 million probable dengue cases in 2026. Of these, 54% are expected in the state of São Paulo. Next year is expected to be the second highest in terms of the number of infections since 2010.
The estimate, which takes into account the 12-month period starting in October 2025, is the result of the InfoDengue-Mosqlimate Dengue Challenge, an international challenge of the InfoDengue and Mosqlimate projects, in partnership with Fiocruz (Fundação Oswaldo Cruz) and FGV (Fundação Getulio Vargas).
Analysis of the next season suggests a year with epidemic characteristics, but without any sign of reaching the incidence extremes observed in 2024.
The study brought together the efforts of 52 researchers from South Africa, Germany, Saudi Arabia, Brazil, Spain, the United States, Italy and the United Kingdom with the aim of supporting the development and training of predictive models for dengue in Brazil and improving predictions of epidemics using climatic and epidemiological data.
In total, 15 research teams participated in the action – called Sprint – with 19 different models predicting dengue cases in Brazil. The predictions were unified.
Projections show that the level will be lower than that observed in 2024 — when Brazil reached more than 6.5 million probable cases and 6.3 thousand deaths from dengue — and similar to that of 2025, which had totaled 1.6 million infections and 1,761 deaths as of December 6.
Acre and Tocantins (north), Rio Grande do Norte (northeast), São Paulo, Minas Gerais and Espírito Santo (southeast), and all federative units in the south and central-west are expected to reach an incidence rate above 300 cases per 100,000 inhabitants, which is considered an epidemic, according to the WHO (World Health Organization).
However, in 2026 it is worth highlighting that Paraná, Rio Grande do Sul, São Paulo, Acre and Amapá are expected to have a lower incidence than that recorded this year. A higher coefficient is expected in Santa Catarina, Minas Gerais, Distrito Federal, Mato Grosso do Sul and Tocantins. The rest will have rates similar to the current analysis projects.
Minas Gerais worries researchers because it is a state where the number of dengue cases has been high in recent years and which, according to projections, is showing growth again.
“There was practically no dengue in the South and for some years the region has always been second in terms of cases. The champions were the Southeast, the Center-West and the Northeast. The Northeast, in recent years, has recorded few cases compared to the Southeast. And the South has a large virgin population, which has never had dengue fever,” explains Kleber Luz, coordinator of the Arbovirus Committee of the SBI (Brazilian Disease Society infectious diseases) and consultant for arboviruses. at PAHO (Pan American Health Organization), WHO branch for the Americas and professor at the Federal University of Rio Grande do Norte. The specialist did not participate in the study.
According to the coordinator of the study and professor at EMAP/FGV (Fundação Getulio Vargas School of Applied Mathematics), Flávio Codeço Coelho, investments in prevention must continue.
“We have positive expectations for next year, because there is not a big increase compared to this year. Climatically we will enter a quiet year. Historically, with La Niña, in the global climate, we have fewer cases of dengue fever in Brazil. Although the numbers remain high, we will have a break there, but the climatic challenges are really serious and there is an increase in the disease due to the increase in average temperatures,” says Flávio.
“In cities that do not have experience with dengue, the population tends to suffer a little more. The diagnosis is more difficult because local doctors do not have experience with the disease and sometimes the municipality is not ready to provide this assistance. Our biggest concern at the moment is this expansion that we call the internalization of dengue. From large centers it is spreading to medium and small towns,” explains Flávio.
For Kleber Luz, Brazil should not exceed two million cases. The infectious disease specialist draws attention to the possibility of the entry of serotype 3, which has not caused an epidemic in the country for more than 17 years. Its return is risky due to the low immunity of the population.
Dengue is an arbovirus transmitted by Aedes aegypti. The disease has four serotypes. When an individual is infected with one of them, they acquire immunity against that virus, but remain susceptible to others.
BUTANTAN-DV
Anvisa (National Health Surveillance Agency) approved this Tuesday (26) the registration of Butantan-DV, a single-dose vaccine against dengue fever manufactured by the Butantan Institute.
The first 1.3 million doses will be allocated by the end of January 2026 to primary health professionals, who work in UBS (Basic Health Units) and when they visit communities.
The idea of the Ministry of Health is to expand the offer of the SUS (Unified Health System) to adults aged 59, then to extend it to other age groups until reaching adolescents aged 15.
Even with the vaccine, investments in prevention must continue, because the Aedes aegypti it is also the transmitter of the chikungunya and zika viruses.
DENGUE
Anyone with a sudden onset of high fever (38°C to 40°C) and at least two manifestations – headache, prostration, muscle and/or joint pain and pain behind the eyes – should consult a health office.
After the critical phase, most recover. In some cases, the disease can progress to serious forms or even death.
Warning signs of severity are intense and continuous abdominal pain, persistent vomiting, accumulation of fluids in body cavities (ascites, pleural effusion, pericardial effusion),
orthostatic hypotension (drop in blood pressure when getting up from a sitting or lying position), feeling faint, lethargy and/or irritability, enlarged liver, bleeding from mucous membranes and
progressive increase in hematocrit.
There is no specific treatment for dengue fever. Rest and hydration are essential.
Flávio Coelho reinforces the importance of using a repellent, especially in summer and when cases occur.
“The repellent is also valid if you suspect dengue, because if it is transmitted to a mosquito, it passes to another person. If you are eligible for the vaccine, I recommend that you do it,” concludes Professor FGV.
About The Author
