High temperatures and extreme weather increase the spread of many pathogens. Migrant mosquitoes have brought chikungunya and dengue viruses to the Mediterranean region.
More than half of known diseases caused by pathogens may occur more frequently as a result of extreme weather and climate change. That’s the conclusion of a review that has just been published in the journal “Nature Climate Change.”
The research team from the University of Hawaii evaluated 830 studies that examined how global warming, drought, floods or heavy rains affect the spread of diseases. To do this, the researchers compared the study results with official lists from health officials, which list a total of 378 known diseases.
The scientists were able to prove that 58 percent of these conditions could be exacerbated by extreme weather or climate change. Diseases that are caused by microorganisms – particularly bacteria and viruses – or toxins from pollen, fungal spores, algae or animals are noted.
Humans and pathogens coming closer together
The links between the climate crisis and diseases are manifold: Drought pushes wild animals closer to habitats, increasing the risk of zoonoses, that is, infectious diseases transmitted from animals to humans. However, drought can also affect sanitation infrastructure, leading to dysentery and typhoid fever.
In addition, the effects of extreme weather can disrupt medical supplies or drinking water systems and weaken the immune system. For example, floods can also force people to move to areas where they are exposed to germs that cause outbreaks of gastroenteritis and cholera.
Exotic mosquitoes, ticks and fleas as carriers
Global warming and changing rainfall patterns are also expanding the spectrum of potential disease vectors such as mosquitoes, ticks and fleas, but so are algae and bacteria, as these thrive better in warmer environments. It can spread malaria, Lyme disease, West Nile virus, and other diseases.
“In Europe, pathogens transmitted by mosquitoes or ticks play a major role,” confirms Renke Luhken, head of the Arbovirus Ecology Working Group, Department of Arbovirology and Entomology at the Bernhard Knoch Institute for Tropical Medicine (BNITM) in Hamburg. “Exotic mosquito species are establishing themselves in large parts of Europe. In particular, the Asian tiger mosquito is responsible for outbreaks of chikungunya virus and dengue virus in the Mediterranean region.»
Rising temperatures favor West Nile virus
At the same time, pathogens transmitted by native mosquito species, such as dog skinworm or West Nile virus, are spreading in Europe. West Nile virus first spread in Germany in the hot summer of 2018. Since then, cases of the disease have been reported in birds, horses and humans every year. The chances of transmission of this virus increase with increasing temperature.
These are just a few examples. The authors of the observational study identified more than 1,000 possible links between climate-related events and the spread of diseases.
“We’re opening Pandora’s box of diseases,” Camilo Mora, research director and geographer at the University of Hawaii, told the Guardian. “There are diseases out there just waiting for them to open up. It’s like beating a lion with a stick – at last the lion comes and bites our butt.”
learning from Mediterranean countries
According to the researchers, preventing or adapting to the increasing spread of diseases caused by the climate crisis is difficult, if not impossible. The pathogens and transmission routes for this abound.
“As the authors also emphasize in their closing statement, measures to reduce greenhouse gas emissions are essential to reduce future risks from pathogens,” demands Luhken. Also, surveillance systems have to be established to be able to record changes in the frequency of diseases at an early stage.
In addition, scenarios for prevention must now be developed, for example to combat mosquitoes. Luhken recommends: “In Central Europe, we can learn a lot from countries in the Mediterranean region or the Global South, which have been battling the pathogens currently spreading for many years.”