Weather hazards such as floods, heat waves and drought have aggravated more than half of hundreds of known infectious diseases in humans, including malaria, hantavirus, cholera and anthrax, study finds .
The researchers scoured the medical literature for established cases of the illnesses and found that 218 of 375 known human infectious diseases, or 58%, appeared to be made worse by one of 10 types of extreme weather linked to climate change, according to a study. study. in Monday’s journal Nature Climate Change.
The study mapped 1,006 pathways between climate hazards and sick people. In some cases, downpours and flooding are making people sick from disease-carrying mosquitoes, rats and deer. There are warming oceans and heat waves that contaminate seafood and other things we eat and droughts that bring bats that carry viral infections to people.
Physicians, dating back to Hippocrates, have long associated disease with climate, but this study shows just how widespread the influence of climate is on human health.
“If the climate changes, the risk of these diseases changes,” said study co-author Dr. Jonathan Patz, director of the Global Health Institute at the University of Wisconsin-Madison.
Physicians, like Patz, have said that they should view illnesses as symptoms of a sick Earth.
“The results of this study are terrifying and illustrate the enormous consequences of climate change on human pathogens”, said Dr. Carlos del Rio, an infectious disease specialist at Emory University, who was not part of the study. “Those of us who work in infectious disease and microbiology must make climate change one of our priorities, and we must all work together to prevent what will undoubtedly be a catastrophe due to climate change. climate.”
In addition to looking at infectious diseases, researchers have expanded their research to look at all types of human diseases, including non-infectious diseases such as asthma, allergies, and even animal bites, to see how many diseases they could associate with climatic hazards in one way or another. , including infectious diseases. They found a total of 286 unique illnesses and of these, 223 appeared to be weather-aggravated, nine were weather-modified and 54 had both worsened and minimized cases, according to the study.
The new study does not do the math to attribute specific changes, ratings or magnitude of illness to climate change, but finds instances where extreme weather was one likely factor among others.
The study’s lead author, Camilo Mora, a climate data analyst at the University of Hawaii, said it’s important to note that the study is not intended to predict future cases.
“There is no speculation here whatsoever”, Mora said. “These are things that have happened before.”
An example that Mora knows firsthand. About five years ago, Mora’s home in rural Colombia flooded – for the first time in his memory, water was in his living room, creating an ideal breeding ground for mosquitoes – and Mora contracted the disease. Chikungunya, a nasty virus transmitted by mosquito bites. And even though he survived, he still feels joint pain years later.
Sometimes climate change acts in strange ways. Mora includes the 2016 case in Siberia when a decades-old reindeer carcass that died of anthrax was dug up when the permafrost thawed due to warming. A child touched it, caught anthrax and started an epidemic.
Mora originally wanted to research medical cases to see how COVID-19 intersects with weather vagaries, if at all. He found instances where extreme weather conditions both exacerbated and decreased the risks of COVID-19. In some cases, extreme heat in poor areas has caused people to gather to cool off and expose themselves to illness, but in other situations, heavy downpours have reduced the spread of COVID because people are stayed home and indoors, away from others.
Kristie Ebi, a longtime climate and public health expert at the University of Washington, warned that she had concerns about how the conclusions were reached and some of the study methods. It is an established fact that the burning of coal, oil and natural gas has led to more frequent and intense extreme weather, and research has shown that weather is associated with many health problems, a- she declared.
“However, correlation is not causation”, Ebi said in an email. “The authors did not discuss the extent to which the climate hazards examined changed over the study period and the extent to which any change was attributed to climate change.”
But Dr Aaron Bernstein, acting director of the Center for Climate, Health and the Global Environment at the Harvard School of Public Health, Emory’s del Rio and three other outside experts said the study is a good warning about the climate and health now and in the future. Especially since global warming and habitat loss are bringing animals and their diseases closer to humans, Bernstein said.
“This study underscores how climate change can load the dice to favor infectious surprises,” Bernstein said in an email. “But of course it only reports what we already know and what is still unknown about pathogens may be even more compelling about how preventing further climate change can prevent future disasters like COVID-19. “
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