Sao Paulo Dengue Outbreak Causes Over 690 Deaths

The São Paulo State Health Department recently confirmed that Dengue is a seasonal disease. During the rainy season, a high transmission rate can be observed. Throughout Brazil, Dengue is the most critical arbovirus disease transmitted by arthropod vectors.

Over the past 25 years, nearly 18 million Brazilians have been infected with Dengue.

As of May 26, 2025, the state of São Paulo, with a population of 44 million, has reported about 617,000 of Brazil's 2.5 million Dengue cases this year. According to data, the state of São Paulo leads in the number of deaths from dengue fever, with 692 cases.

In February 2025, a public health emergency was declared to alert residents and international visitors of this continuing health risk.

Last year, about 2.1 million Dengue cases and 2,100 related fatalities were reported in São Paulo.

This ongoing surge is related to Dengue virus serotype 3 (DENV-3) reemergence since the population is not immunized against this serotype.

While a second-generation Dengue vaccine will be limited in availability in 2025, Butantan Institute in São Paulo has been involved in developing an innovative vaccine that could become available in 2026.

Additionally, with the annual influenza season arriving in South America, beginning on May 27, 2025, the flu vaccination will be offered to the entire population in São Paulo's 645 municipalities over six months of age.

When visiting Brazil in 2025, the U.S. CDC recommends international travelers speak with a travel vaccine expert about various immunization options, such as chikungunya and yellow fever.