Increase in dengue cases is linked to climate change and deforestation in Brazil

The constant heat waves caused by climate change, combined with incomplete urbanization and the large circulation of people in certain areas, are influencing the spread of the dengue fever into the hinterlands of the country. This is revealed by the study Climate change, thermal anomalies, and the recent progression of dengue in Brazil, published on Nature's Scientific Reports portal. The text was written by researcher Christovam Barcellos, from the Climate and Health Observatory of the Institute of Scientific and Technological Communication and Information in Health (Icict/Fiocruz).

In the article, Barcellos points out that dengue has been spreading to the South and Midwest regions, where the disease was not so common. This is due to the increase in extreme weather events, such as droughts and floods. Another decisive factor would be environmental degradation, especially in the Cerrado, which has been suffering from deforestation, fires and the conversion of forests into pasture.

"In the hinterlands of Paraná, Goiás, the Federal District and Mato Grosso do Sul, the rise in temperatures is becoming almost permanent. We used to have five days of heat anomaly, now there are 20, 30 days of above-average heat during the summer. This triggers the dengue transmission process, both because of the mosquito and because of the circulation of people," Barcellos explains. "In these regions suffering from high temperatures, we have also seen very rapid deforestation. And within the Brazilian Cerrado, there are cities already with heat islands, suburban areas or outskirts with poor sanitation conditions, making it more difficult to fight the mosquito."

The study used data mining techniques to assess the correlation between thermal anomalies, demographic factors and changes in dengue incidence patterns over a 21-year period (2000-2020) in Brazil's micro-regions. The article is also signed by researchers Vanderlei Matos, from the Climate and Health Observatory at the Icict/Fiocruz; and Rachel Lowe and Raquel Martins Lana, from the Barcelona Supercomputing Center, with which the Observatory maintains technical cooperation through the Harmonize project.