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Spread of illnesses can be exacerbated by climate change, study finds

As if climate change and diseases like Covid-19 weren’t troubling enough threats on their own, researchers have discovered that the two may be connected.

(CN) — Amid a seemingly never-ending global pandemic, many people have searched for an answer as to how diseases can persist in our communities for so long. In a study published Monday, scientists at the University of Hawaii link disease to the similarly never-ending effects of climate change.

The study, led by Camilo Mora of the University of Hawaii, quantified that 58% of all infectious diseases, including influenza and Covid-19, have at some point been aggravated by climate change. The study does qualify that the spread of disease is obviously complex and can depend upon the relationship between biological and environmental factors, but shows that climate change does have an undeniable connection to the spread and severity of pathogenic disease.

Authors of the study analyzed a matrix of tens of thousands scholarly records and identified 286 unique pathogenic diseases that were associated with climate hazards, over half of which had been affected by the hazards.

“We would parse those articles that would come up and make sure that they weren’t just predicting something that might occur but that they were solid evidence of ‘this disease increased due to a flood that occurred in a certain place at a certain time’. Just making sure we had solid evidence and solid cases of the increased diseases,” explained Renee Setter, a PhD student at the University of Hawaii at Manoa with the Department of Geology and Environment and a co-author of the study.

Authors mapped climate hazards like global warming, storms, or floods and droughts against disease triggers including viruses and bacteria, as well as even plants and animals. Over 1,000 permutations of the interplay between these various climate hazards and disease vectors were documented in a Sankey plot published with the study itself.

Climate change has caused fluctuations in temperature and precipitation, affected sea levels and brought more extreme weather patterns globally. These changes have brought human populations into new and increased proximity to a variety of disease vectors, like mosquitos and ticks, among others. These vectors are typically associated with potentially deadly diseases including dengue fever, Lyme disease, malaria and West Nile virus.

A swim in the lake may seem like the perfect relief for people worldwide experiencing unprecedented heatwaves, but study authors encourage caution. Efforts to beat the heat may increase exposure to skin infections, as well as Legionnaire’s, giardia, or other waterborne diseases.

Not only does climate change bring people closer to disease, it can also have the unfortunate effect of strengthening those diseases. Data collected by the team of researchers indicate that global warming in particular affects the transmission and intensity of infectious disease more than other factors.

The study also touches on the possible effect on Covid-19, citing instances where the amount of cases increased or decreased based on weather.

Setter clarified in an interview with Courthouse News, “I don’t know that we can say that Covid is attributed to climate change but what we can say for sure is there has been an increase in diseases due to some of these climate hazards, and with the increase of these climate hazards we might see more of these diseases occurring in the future.”  

The study does note that there was a division of diseases that climate change had an opposite effect on. For 63 out of the 286 diseases studied, climate change actually lessened the spread of those diseases. While it may seem reassuring, the study also says, “we also found that most diseases that were diminished by at least one hazard were at times aggravated by another and sometimes even the same hazard.”

The study concludes with an emphasis on the threat to human health and the increasing need to mitigate the effects of climate change, a sentiment echoed by Setter.

“One of the things we need to be more cautious of, on a policy level, we need to have governments ready to tackle these issues, ready to come to action quickly, so that we can address if we know that temperatures might be increasing in a certain area, maybe this is going to lead to the increase of a certain type of disease, and just be prepared to address the issues,” she said.

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