The Pan American Health Organization (PAHO) issued epidemiological alert on the high risk of type 3 dengue outbreaks in the Americas. According to the entity, the circulation of serotype has already been recorded in several countries of the continent – including Brazil, Colombia, Costa Rica, Guatemala, Mexico and Peru.
“PAHO asks countries that reinforce their surveillance, early diagnosis and clinical management so that they can face a potential increase in dengue cases,” the organization said in a statement. The statement also mentions that Argentina even recorded some cases of type 3 dengue in 2024.
Dengue virus has, in all, with four distinct serotypes, and immunity against a serotype offers lifetime protection only against this specific serotype. “Which means that subsequent infections with other serotypes can increase the risk of serious forms of the disease.”
“The appearance or increased circulation of a serotype that was not prevalent in a region may lead to an increase in dengue cases due to the greater susceptibility of the population,” said PAHO. In Brazil, Sorotype 3 has not predominantly circulating since 2008.
Also according to the entity, serotype 3 has been associated with severe forms of the disease, even in primary infections (when the patient has no history of infections by other dengue serotypes). “The scenario raises concerns about the potential impact of Sorotype 3 on public health.”
“The resurgence of serotype 3, after a period of prolonged absence in certain areas of the Americas, increases the vulnerability of populations that have not been previously exposed to it,” said PAIDS.
Numbers
In 2024, the Americas reported more than 13 million dengue cases, 22,684 classified as severe dengue (0.17%), plus 8,186 deaths associated with the disease.
In the first weeks of 2025, 23 countries and territories of the Americas count 238,659 cases of dengue, most concentrated in Brazil (87%). Then are Colombia (5.6%), Nicaragua (2.5%), Peru (2.5%) and Mexico (2.5%). Of the total cases, 263 were classified as severe dengue, plus 23 confirmed deaths.
