Deforestation accelerates dengue epidemic in Brazil: Impacts of global warming in focus

Deforestation accelerates dengue epidemic in Brazil: Impacts of global warming in focus

Published On: 26 de April de 2024

Brazil is facing a public health crisis with the rise in cases of dengue fever, a disease transmitted by mosquitoes that breed in stagnant waters. The country is ravaged by an epidemic with more than 2.3 million probable cases of the disease registered by the end of March this year, and experts point to a worrying relationship between the increase in deforestation and the proliferation of the disease vector.

According to a new study published by researchers from the Oswaldo Cruz Foundation (Fiocruz) in the journal Scientific Reports, the constant increase in dengue cases in areas where the disease was previously rare is directly linked to frequent heat waves caused by climate change and the expansion of human occupation in recently deforested areas.

“In the interior of Paraná, Goiás, Distrito Federal and Mato Grosso do Sul, the increase in temperatures is becoming almost permanent. We had five days of heat anomaly, now there are 20, 30 days of heat above average throughout the summer. This triggers the dengue transmission process, both because of the mosquito and the movement of people”, explains Christovam Barcellos, a researcher at Fiocruz and one of the authors of the study. “In these regions that are suffering from high temperatures, we have also seen very accelerated deforestation. And within the Cerrado, there are cities that already have heat islands, suburban areas or outskirts with poor sanitation conditions, making it more difficult to combat mosquitoes.”

This chaotic scenario has generated an urgent warning about the need to confront not only the disease, but also its underlying causes. Above-average temperatures during the summer, intensified rainy season and the influence of El Niño in Brazil, insufficient investment in preventive measures in recent years, deficiencies in the basic sanitation system and expansion of irregular urban occupations, increased deforestation in several regions of the country , are some of the factors that have contributed to the increase in dengue.

The mosquito, Aedes aegypti, develops better in higher temperatures and with regular amounts of rainfall. With global warming, hot and humid weather has become more frequent compared to past years, transforming areas previously considered inhospitable for mosquitoes into favorable ones for their survival and proliferation.

Urban centers and their heat islands easily have temperatures between 18° and 33°C, ideal conditions for the life and proliferation of the Aedes aegypti mosquito. However, parks and tree-lined squares can reduce the temperature by up to 4 degrees, which reduces the presence of mosquitoes, in addition to the fact that these places tend to have greater biodiversity with predators that feed on mosquitoes, and other species that compete for the least niche. .

Given the growing interconnection between human health and environmental health, there is an urgent need to adopt holistic approaches that recognize the complex links between deforestation, climate change and vector-borne diseases. Otherwise, Brazil runs the risk of facing even more serious epidemics in the future, with devastating consequences for public health and the environment.

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