Experts in the field of infectious diseases have called on their fellow members of the medical community to take proactive measures after finding a strong relationship between an evolving climate and the spread of diseases.
What's happening?
In their article published in JAMA on March 20, and shared by UC Davis Health, the researchers outlined four categories of illnesses that have altered in range and active period because of human-driven changes in weather patterns: vector-borne, zoonotic, fungal, and waterborne diseases.
Vector-borne diseases are carried by blood-feeding arthropods, like ticks, fleas, and mosquitoes.
Shorter, milder winters and longer summers have allowed ticks to spread diseases like Lyme and babesiosis during the typically colder months and in areas further north and west.
"We're seeing cases of tick-borne diseases in January and February," said Matthew Phillips, an infectious diseases fellow at Massachusetts General Hospital and Harvard Medical School and study author. "The tick season is starting earlier and with more active ticks in a wider range. This means that the number of tick bites is going up and with it, the tick-borne diseases."
Phillips added that the surge in domestic malaria cases spurred by infected mosquitoes was "one of the scariest things that happened last summer," popping up in Texas, Florida, and as far north as Maryland.
Zoonotic diseases — ones transmitted to humans by animals — have shifted in incidence and location following changes in animals' migratory habits and natural ranges. Habitat loss has compounded the issue, increasing the risk of plague and hantavirus.
A changing climate has also led to new fungal infections like Candida auris while proliferating fungal pathogens. Valley fever was endemic to the hotter and drier portions of California and Arizona but has since been diagnosed in the state of Washington.
Additionally, E. coli, Vibrio, and other waterborne diseases have expanded their coverage as a result of extreme weather, changing rain patterns, rising sea levels, and warming ocean temperatures.
"Clinicians need to be ready to deal with the changes in the infectious disease landscape," said lead author George R. Thompson, a professor at the UC Davis School of Medicine. "Learning about the connection between climate change and disease behavior can help guide diagnoses, treatment, and prevention of infectious diseases."
Why is the spread of diseases concerning?
The most obvious repercussion of the current predicament is the exposure of diseases to populations that have yet to immunize themselves.
Furthermore, an increase in cases would burden a healthcare system that is already overburdened.
For example, Lyme disease in the U.S. can cost up to $1.3 billion annually. A report from the World Economic Forum estimates that it will cost the global healthcare industry $1.1 trillion over the next 26 years to cover the treatment for diseases enabled by a warming planet.
What's being done about the spread of diseases?
Thompson insisted that physicians and practitioners retain "a high index of suspicion of diseases on the move." "I think with improvements in our understanding of the disease, there will be more testing, and we'll miss fewer cases that way," he said.
Additionally, the researchers would like to increase surveillance for infectious diseases and called on medical educators to train clinicians to follow disease patterns and remain proactive instead of reactive.
"It's not a hopeless situation. There are distinct steps that we can take to prepare for and help deal with these changes. Clinicians see firsthand the impact of climate change on people's health. As such, they have a role in advocating for policies that can slow climate change," Phillips said.
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