Yellow fever and dengue cases surge in South America as climate crisis fuels health issues | Climate crisis

The surge in cases of yellow fever and dengue fever in South America highlights the growing assault the climate crisis is taking on people’s health, with infectious diseases spread by mosquitoes and deadly heat now also spreading to temperate regions like Europe, experts warned at the Cop30 climate summit.

There have been 356 cases of yellow fever in South America and 152 deaths so far this year, mainly in the Amazon region, according to figures from the Pan American Health Organization. Apart from a significant peak in 2017 and 2018, this is the highest number of yellow fever cases for a year on the continent, bar one, since 1960.

The current wave of yellow fever, which can cause fever, nausea and even organ failure, comes after one of Brazil’s worst years of dengue fever. In 2024, almost 6.5 million cases of dengue and around 5,000 deaths have been reported in Brazil. Last year was also a record year for dengue in Europe, with 304 cases reported, more than the 275 cases reported in the previous 15 years combined.

Yellow fever and dengue are transmitted by the Aedes mosquito species, which thrives in warm conditions and stagnant water. The climate crisis, which is raising global temperatures and causing more ferocious rainfall, is making about half of known human pathogens worse, scientists have determined, as disease-carrying mosquitoes expand their range in a rapidly warming world.

The sharp rise in communicable diseases in the Amazon region comes as UN climate negotiations take place in Belém, a Brazilian city near the mouth of the Amazon River.

Health was, until a few years ago, a largely neglected area of ​​the climate crisis at these annual summits, but the UN declared Thursday “Health Day” at Cop30 and promoted a new plan to help countries deal with the range of diseases and life-threatening conditions brought on by a hotter world.

“Across the world, people are experiencing the daily reality that the climate crisis is also a public health crisis,” said Simon Stiell, UN climate chief. “Rising temperatures, floods, droughts and storms are killing people, fueling disease and malnutrition and putting immense pressure on health systems. »

Stiell said the new Belém Health Action Plan, led by the Brazilian government and the World Health Organization, will help countries with surveillance, best practices and capacity building to help them address climate-related health issues. A coalition of 35 philanthropic organizations has pledged $300 million in funding for the initiative.

“Humanity can only win this global fight against climate if we link stronger climate actions to people’s top priorities in their daily lives,” Stiell said. “And there are few priorities higher than our health. »

But climate advocates and health experts say much more will need to be done to address the consequences of scorching temperatures and worsening disasters such as flooding. On Wednesday, Al Gore, the former US vice president, said recent evidence that rising heat is killing one person every minute around the world shows that governments are woefully failing to reduce the direct human harms of the climate crisis.

“How long are we going to stand by… keep turning up the thermostat for these kinds of events to get even worse?,” Gore said.

Health experts said several factors are driving the expansion of infectious diseases, such as the destruction of forests for agricultural and residential purposes, bringing humans closer to animals that can spread zoonotic diseases.

“It’s also globalization and it’s also the fact that mosquitoes are intelligent, just like bacteria,” said Maria Guevara, international medical secretary of Médecins Sans Frontières, which is present at the Belem rally.

“And whether it’s bacteria or viruses, they transmit, they’re just smarter than humans in this case because they’re more adapted, and they will adapt to survive. We’re way too slow. We know what we need to do about climate change, but we’re doing nothing.”

Guevara said much more will need to be done to equip countries experiencing outbreaks made worse by extreme weather. In recent years, MSF has had to respond to yellow fever epidemics in Brazil and the Democratic Republic of Congo, following severe droughts or floods. Vaccine distribution can be difficult even in countries like Brazil, where yellow fever vaccinations are free.

“We have had huge outbreaks of dengue fever and an increase in yellow fever even outside the Amazon region due to a lot of rain and high temperatures, which makes mosquitoes bite more and affects the reproduction of the virus in mosquitoes,” said Rachel Vicente, an expert at the health sciences center at the Federal University of Espírito Santo in Brazil.

“People are also living near more breeding sites, especially in urban areas of Brazil. It’s a perfect storm and it’s not just a problem of tropical areas anymore, we’ve had outbreaks in Europe because it’s warmer there and it becomes easier for the vector.”

“We all need to work together more on resilience because all countries will need to prepare now, not just some. »