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Human pathogenic diseases aggravated by climate change

Climate CAT events such as flooding, heat waves and drought have worsened more than half of the hundreds of known infectious diseases such as malaria, hantavirus, cholera and even anthrax according to a new research study.

The new research published in the scientific journal Nature in August 2022 has found that 58% of the known human infectious diseases, or 218 out of 375, had at some point been aggravated by at least one of 10 types of climate hazards impacted by greenhouse gas emissions.

A much smaller percentage of the diseases - 16% - were diminished by climate hazards. Over 1,000 disease transmission pathways were observed in the study.

Sifting through medical literature of established cases of illnesses, the researchers found cases of diseases such as Zika, malaria, Lyme disease and even COVID-19 had been aggravated by climate impacts from heat waves to floods.

The researchers presented the cases in groups depending on if climate hazards brought pathogens closer to people, brought people closer to pathogens, strengthened pathogens or weakened a person's ability to cope with pathogens.

In the circumstances where climate hazards bring pathogens closer to people, researchers highlighted spillover from viruses, or when a virus jumps from one species to another, were associated with habitat disruptions, forcing animals -- and any diseases they carry - closer to people.

Nipah virus and Ebola, two such spillover viruses, were associated with wildlife like bats, rodents and primates moving over larger areas foraging for limited food after drought or searching for new habitats following wildfires.

On the other hand, climate hazards also impact human behaviour and travel, resulting in either a heightened chance for pathogens to spread or isolation from new hosts. Past studies have noted that changes in precipitation and temperature affected human social gatherings and the transmissibility of viruses like influenza and COVID-19.

Climate hazards also enhanced specific aspects of pathogens, according to the study. This includes improving climate suitability for reproducing, accelerating the pathogen's life cycle, increasing the length of seasons and likely exposure, allowing for organisms carrying the pathogen to more easily spread and increasing virulence.

The weather events have also played a role in impacting a person's ability to fight off disease through exposure to hazardous conditions, reduced access to medical care or forcing people into unsafe conditions.



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