Climate change is worsening more than half of infectious diseases
As the world continues to reel under the impact of Covid-19 and several countries battle the outbreak of Monkeypox, new research paints a grim picture of the connection between climate change and infectious diseases.
The study, published by the journal Nature Climate Change, revealed that 58% of known human infectious diseases have been worsened by extreme weather events, such as floods or heatwaves.
Researchers looked through the medical literature of established cases of illnesses of the known 375 human infectious diseases. They found that 218 of them, such as malaria, hantavirus, cholera, and anthrax, had worsened by extreme climate.
In addition to looking at infectious diseases, the scientists expanded their search to other types of human illnesses, such as asthma, allergies, and even animal bites to see how many diseases they could connect to climate hazards.
They found a total of 223 illnesses that seem to be worsened by extreme weather events, but they also found others that were diminished by climate conditions.
An example of a disease diminished by climate conditions could be seen with Covid-19. Heavy downpours reduced Covid spread because people stayed home and indoors, away from others.
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But in other situations, heavy downpour causes flooding, which creates an ideal breeding ground for mosquitoes.
An example of this comes from the lead author of the study, Camilo Mora, who after experiencing a flood in his home in Colombia, contracted Chikungunya, a nasty virus spread by mosquito bites, which would cause him joint pains for years to come.
Doctors, going back to Hippocrates, have long connected disease to weather, but this study shows how widespread the influence of climate is on human health.
“If the climate is changing, the risk of these diseases is changing”, said study co-author Dr. Jonathan Patz, director of the Global Health Institute at the University of Wisconsin-Madison.
“The findings of this study are terrifying and illustrate well the enormous consequences of climate change on human pathogens”, said Dr. Carlos del Rio, an Emory University infectious disease specialist.
“Those of us in infectious diseases and microbiology need to make climate change one of our priorities, and we need to all work together to prevent what will be, without a doubt, a catastrophe as a result of climate change”, added del Rio.
Study lead author, Camilo Mora, a climate data analyst at the University of Hawaii, said what is important to note is that the study isn't about predicting future cases. "There is no speculation here whatsoever," Mora said. "These are things that have already happened."
However, longtime climate and public health expert Kristie Ebi at the University of Washington cautioned that she had concerns with how the conclusions were drawn and some of the methods in the study.
Image: Ux Indonesia/Unsplash
“Correlation is not causation”, Ebi said to CNBC. “The authors did not discuss the extent to which the climate hazards reviewed changed over the time period of the study and the extent to which any changes have been attributed to climate change”.
Image: Alvaro Reyes/Unsplash
However, Dr. Aaron Bernstein, interim director of the Center for Climate, Health, and the Global Environment at Harvard School of Public Health, and three other outside experts, said the study is a good warning about climate and health for now and the future.
“This study underscores how climate change may load the dice to favor unwelcome infectious surprises”, Bernstein told CNBC. “But of course, it only reports on what we already know and what is yet unknown about pathogens may be yet more compelling”.
Recently, a team of international scientists said the world needs to start preparing for the possibility of a “climate endgame” as extreme weather events keep ravaging the planet.
“Right now, I think we're being naive. We're not looking at the worst-case scenarios at all, really”, said one of the scientists, Luke Kemp, of Cambridge's Centre for the Study of Existential Risk.
The report by Kemp and his colleagues warned about the risk of a climate-driven increase in infectious diseases as well as the risks of famine, extreme weather disasters, and conflict over resources.
The number of weather-related disasters to hit the world has increased five-fold over the past 50 years, according to the World Meteorological Organization. However, the number of deaths because of natural disasters has fallen sharply, thanks to improved early warnings and disaster management.
Furthermore, a 2021 study, published in the Lancet Planetary Health, showed that more than 5 million people die each year globally because of excessively hot or cold conditions. But while cold-related deaths are decreasing, heat-related ones are on the rise.