Brazil dengue 2025: The first three weeks

Case count

In 2024, Brazil reported record numbers in dengue fever including almost 6.49 million probable cases of the disease, with 5,972 deaths.

Through the first 22 days of 2025, the Ministry of Health has recorded 99,000 probable cases, including 12 deaths and another 113 deaths under investigation.

Like in 2024 when São Paulo state recorded the most cases (2,119,837 confirmed cases of dengue fever, the highest number recorded since 2000, when the historical series began), São Paulo has recorded the most cases through January 22, 2025 with more than 57,000 cases.

At the beginning of the year, the Minister of Health, Nísia Trindade, set up the Public Health Emergency Operations Center for Dengue and other Arboviruses (COE Dengue). The idea is to coordinate planning and response through constant dialogue with states, municipalities, researchers and scientific institutions, as well as other departments.

The planned actions include anticipating the dengue season to adapt health networks; mitigating risks to avoid cases and deaths; expanding preventive measures to better prepare states and municipalities, in addition to a national coordination to respond to possible situations classified as critical.

Data from the ministry indicate that, by 2025, there is a forecast of an increase in the incidence of dengue cases in at least six Brazilian states: São Paulo, Rio de Janeiro, Espírito Santo, Tocantins, Mato Grosso do Sul and Paraná. All of them, according to the ministry, are being monitored “even more closely”.

Rapid dengue tests

The Ministry of Health will distribute 6.5 million rapid tests to diagnose dengue fever in all states of the country. This is the first time that the ministry has sent this type of test to detect dengue fever. The initiative will increase early identification of cases, especially in remote municipalities with limited access to laboratory services. The investment totals more than R$17.3 million. Distribution will begin next week and state managers will be guided by means of a technical note with criteria for use.

Of the total, 4.5 million tests will be distributed in the first shipment. The remaining two million tests will be used as strategic stock to serve locations that may experience an increase in the number of cases and require a rapid response in diagnosis. The process of acquiring rapid tests was initiated in 2024.

The Unified Health System (SUS) already has two other types of tests for identifying dengue fever: molecular biology and serological tests, both available at the Central Public Health Laboratories (Lacen). With the announcement by the Ministry of Health, the population now has a third option, which is the rapid test, capable of detecting the presence of the dengue virus, but without identifying the serotype. These tests will be available in the public network, such as Basic Health Units, according to the distribution of local management.

Dengue serotype 3

Dengue serotype 3 has seen an increase amid positive tests for the disease in Brazil – especially in the states of São Paulo, Minas Gerais, Amapá and Paraná. The increase was recorded mainly in the last four weeks of December. The situation is worrying Brazilian health authorities, since the virus has not circulated predominantly in the country since 2008 and, consequently, a large part of the population is susceptible.

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“DENV-3 is considered one of the most virulent serotypes of the dengue virus, meaning it has the greatest potential to cause severe forms of the disease. Studies indicate that after a second infection by any serotype, there is a predisposition to more severe symptoms, regardless of the sequence of serotypes involved. However, serotypes 2 and 3 are often associated with more severe manifestations.”

According to the ministry, the introduction of a new serotype into a population previously exposed to other dengue serotypes could lead to a scenario of “significant epidemics”. The increase in the incidence of dengue recorded between 2000 and 2002, for example, was associated with the introduction of DENV-3. Throughout 2024, the predominant serotype in Brazil was 1, identified in 73.4% of the samples.