How climate change promotes the spread of disease

.Man-made climate change clearly favors the spread and emergence of infectious diseases. This is underlined by a study by the University of Hawaii published Monday (08/08) in the scientific journal Nature Climate Change. “It was really scary to see that greenhouse gas emissions are such a big health threat,” said Camilo Mora, a professor in the University of Hawaii’s College of Social Sciences and lead author of the report. ‘study.

By evaluating more than 800 scientific papers, the researchers found that 58% of the infectious diseases analyzed were exacerbated by climate change. And a link could be proven in more than 3,000 individual cases.

According to the study, of the 375 diseases analyzed, 160 can be aggravated by heat, 121 by floods, 71 by storms, 81 by drought and 43 by warming oceans. “Given the deep and widespread consequences of the Covid-19 pandemic, it was truly frightening to discover the enormous health vulnerability resulting from greenhouse gas emissions,” adds Mora.

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Droughts, storms and heat waves

The links between climate change and disease can be varied: water and food shortages caused by droughts can, for example, bring wild animals closer to residential areas, increasing the risk for individuals of contracting an animal-borne disease. or parasites. Droughts can also end up causing people to drink contaminated water, which can cause illnesses such as diarrhea or cholera.

In turn, storms, heavy rains and floods can damage roads, power lines and sewage systems, as well as interrupt the supply of drinking water. Such events have already caused epidemics of hepatitis A and E, rotavirus and typhoid fever. Another point is that the immune system can be weakened, for example, due to malnutrition caused by drought or heat waves, which makes you more vulnerable to disease.

Stress from other extreme weather events can also weaken the immune system of humans and animals. Researchers have found, for example, that heat and lack of food in bats lead to increased spread of the virus and promote outbreaks of the Hendra virus – which can cause severe encephalitis in humans.

In total, scientists have identified more than a thousand different ways in which climate change could promote epidemics. Mosquitoes adapted to Europe Higher temperatures can not only promote the spread of pathogens and increase the risk of infection, but also promote the spread of carriers, the so-called warmer vectors. Due to rising temperatures, they can now live in areas where they were not native to before.

The study revealed more than 100 vector-borne diseases that are intensifying with climate change. “We have already observed in Germany and Europe the influence of climate change events on pathogens,” says Renke Lühken of the Bernhard Nocht Institute for Tropical Medicine (BNITM) in Hamburg in an interview with DW .

The virologist specializes in insect-borne diseases and was not involved in the study. According to Lühken, experts are particularly concerned about the spread of the Asian tiger mosquito (Aedes albopictus). It is currently establishing itself in a large part of Europe and “is notably responsible for epidemics of chikungunya virus and dengue fever in the Mediterranean region”, adds the virologist.

“It is very aggressive and assertive: it is able to transmit more than 20 different viruses to humans and displace native species of mosquitoes. It is also very adaptable when it comes to choosing suitable breeding sites”, explains Artur Jöst, biologist and mosquito specialist at the Institute of Dipterology in Speyer, Germany.

An aggressive approach is needed

The Zika virus and dengue fever cause high fever, rashes and severe headaches, in the bones and in the body. In a 2020 study, researchers from the University of Georgia in the US warned that by 2050 more than 1.3 billion people will be living in areas where Zika can spread. More than 700 million people will live in temperatures that allow transmission throughout the year. “It’s worrying, because there are only approved vaccines for some of these pathogens,” says BNITM’s Lühken. Vectors transmit 17% of all infectious diseases. Nearly 700 million people contract mosquito-borne diseases every year and more than a million die from them. According to the authors of the Nature Climate Change article, it is difficult, if not impossible, to prevent – or adapt to – the increased spread of diseases due to climate change, as there are so many pathogens and transmission routes. . For the experts, we therefore need an “aggressive approach” in order to reduce greenhouse gas emissions. Author: Tim Schauenberg

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