Dengue cases almost triple in Brazil due to El Niño and the climate crisis

Brazil is on alert due to the increase in cases of denguewhich have almost tripled at the beginning of January, according to data released this Thursday, an expansion caused by the rains and high temperatures associated with the El Niño phenomenon and the climate crisis and which could lead the country to break records this year.

In the first three weeks of January, 120,874 cases were recorded and an incidence of 59.5 per 100,000 inhabitants, a figure that far exceeds the 44,753 cases in the same period of 2023, according to data from the Ministry of Health released this Thursday.

The medical bulletin also includes 12 confirmed deaths and 85 under investigation in these first three weeks of the year.

The health authorities’ forecast is that between 1.7 and 5 million cases will be recorded this year, which would be a record for this disease transmitted by a mosquito.

Brazil had already had one year, 2023, with 1.6 million cases, more than a fifth of all those reported in the world, and just over 1,000 deaths, a historical record.

The high temperatures associated with El Niño since mid-2023 and, in general, climate change, shorten the development time of the mosquito by half, Tamara Nunes de Lima-Camara, associate professor of epidemiology at the University of São, explains to EFE. Paul.

“In addition, the increase in temperatures has expanded the mosquito’s distribution area. In Brazil you have many more cases of dengue than before in the southern region, which is the coldest, due to climate change“, says.

The state of Rio Grande do Sul, bordering Uruguay and Argentina, went from having 436 cases in 2002 to 38,657 last year.

Added to this is the reappearance of a dengue variant that has not been seen for ten years in São Paulo and for which the younger population is not immunized as they have not previously been infected with it.

Faced with this situation, large cities have begun to spray the streets with insecticide. In São Paulo, the City Council has purchased 30 vehicles for spraying and has hired 700 officials to carry out house-to-house inspections.

In Brasilia, Esther Carneiro, a 41-year-old housewife, lines up with 40 other people in front of a tent to be tested for dengue and receive medication if she tests positive.

“There is a general outbreak in my neighborhood and they have not yet started fumigating“, she tells EFE, worried.

The race for the vaccine

Specialists such as Julio Croda, infectious disease specialist at the Oswaldo Cruz Foundation (Fiocruz) and president of the Brazilian Society of Tropical Medicine, say that these traditional measures are not enough.

“Control tools such as fumigation have not been sufficient and case records are broken year after year in Latin America. What is needed is investment in science and technological innovations”, he points out.

One of these innovations, implemented in eleven municipalities by Fiocruz, is the release of mosquitoes to which a bacteria is introduced that reduces their ability to transmit dengue.

A study published in the Public Library of Science on the effects of the program in Niterói, a neighboring city of Rio de Janeiro, shows a 69% reduction in incidence three years after its launch.

However, the most powerful weapon is vaccines. The Brazilian Government plans to purchase up to 6.2 million doses of a Japanese vaccine in 2024, which will begin to be administered free of charge to children and adolescents starting in February.

However, as it is a double dose, this amount only covers 3.1 million people and is insufficient to face the current explosion of cases.

In order not to depend on foreign laboratories, the Butantan Institute, a research center located in São Paulo, is developing a single-dose vaccine and whose clinical trials already point to a general efficacy of 79%.

“The initial data is promising, but we will still have large transmission for two or three years until sufficient doses are available.”says Croda.