Scientists say climate change could exacerbate more than half of known human pathogens

Scientists have made a disturbing discovery about how global warming is affecting known infectious diseases.

Climate risks are expected to exacerbate 58% of all known human pathogens, according to a study published Monday in Nature Climate Change. This represents more than half of the infectious diseases detected since the end of the Roman Empire, Camilo Mora, a data analyst and assistant professor in the Department of Geography and Environment at the University of Hawaii Manoa, told ABC News.

While the impact that climate change can have on human exposure to a range of diseases has been well accepted, the full threat that climate change poses to humanity in the context of disease is unknown, according to the researchers. Previous studies have focused primarily on specific groups of pathogens, such as bacteria or viruses, responses to specific hazards, such as increased heat waves or floods, or types of transmission, such as food or waterborne transmission.

Mora’s team systematically examined the literature revealing 3,213 experimental cases linking 286 unique human pathogens to 10 climate risks, such as global warming, floods or droughts. Of these, 277 pathogens were found to be exacerbated by at least one climate risk, with only nine pathogens “exclusively diminished” by climate risks, according to the study.

Photo: A car drifted in Squabble Creek due to flooding in Buckhorn, Ky.  , August.  5, 2022.

A car drifted in Squabble Creek due to flooding in Buckhorn, Ky. , August. 5, 2022.

Saul Young / News Sentinel via USA Today

Mora said that 58% of a reliable list of infectious diseases that have been documented to affect humanity has already been shown to have been exacerbated by climate hazards — a finding the researchers found “shocking.”

Examples of hazards include those that bring humans close to pathogens, such as storms and floods, which then cause displacements associated with cases of Lassa fever or Legionnaires’ disease.

Another example is events that bring pathogens closer to humans, as warming increases in areas where disease-transmitting organisms are active, such as Lyme disease, dengue fever and malaria.

Photo: Sunflowers grow in a field during a drought, July 31, 2022.

Sunflowers grow in a field during a drought, July 31, 2022.

Pablo Blazquez Dominguez / Getty Images

There is wide taxonomic diversity for human disease-causing diseases, such as bacteria, viruses, animals, plants, fungi, and parasites, as well as the types of transmission – eg, airborne and direct contact – that can be affected by high temperatures, heat waves, droughts, wildfires, extreme rains, floods, and high temperatures. sea ​​level.

Shifts in the geographical range of species are one of the most common environmental indicators of climate change, according to the study. For example, changes in warming and precipitation have been associated with the expansion of vectors such as mosquitoes, ticks, fleas, birds, and many mammals, which have subsequently been implicated in outbreaks of viruses, bacteria, animals, and protozoa, including dengue, chikungunya, plague, Lyme disease, West Nile virus, Zika, Trypanosoma, echinococcosis and malaria.

Researchers have found 1,006 unique pathways in which climatic hazards, across different types of transmission, reside in disease-causing conditions.

Warming at higher latitudes has allowed vectors and pathogens to survive the winter, exacerbating outbreaks of several viruses, such as an anthrax outbreak in the Arctic Circle that may have been caused by an ancient bacterial strain that emerged from the carcass of an animal discovered during a thaw Frozen Earth, according to studies.

Mora said COVID-19 is an example of how a single disease can objectively change a community, adding that he doesn’t believe that the most recent epidemic — and the animal-to-human transmission that most likely caused it — could have had an event without global warming.

Photo: An aerial view of pancake ice and melting in the Arctic, July 19, 2022.

An aerial view of pancake ice and melting in the Arctic, July 19, 2022.

Kerem Yucel/AFP via Getty Images, FILE

Mora said this research reveals more evidence that humans will have a hard time adapting to climate change, especially those in developing countries.

“The magnitude of vulnerability when you think about one or two diseases — well, sure, we can handle that,” he said. “But when you talk about 58% of diseases, and 58% of these diseases can be affected or occur in a thousand different ways. So, for me, that was also revealing about the fact that we will not be able to adapt to climate change.”

Mora said extreme weather events such as droughts and wildfires in the west, floods in both inland and coastal areas, and extreme heat in places that had not previously experienced high temperatures are becoming more common.

The authors said the findings reveal unique pathways in which climate risks can lead to disease, underscoring limited societal adaptive capacity, and underlining the need to reduce greenhouse gas emissions.

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