The infectious disease landscape is changing, and we must prepare

A team of infectious disease specialists has issued an urgent call to action for the medical community, emphasizing the need for heightened awareness and preparedness to address the rising impact of climate change on disease transmission and outbreaks. 

The study was led by the University of California Davis (UC Davis), Harvard University and the Massachusetts General Hospital, 

Imminent threats posed by emerging pathogens 

The experts highlighted the imminent threats posed by emerging pathogens and the critical role of healthcare professionals in mitigating these challenges through enhanced education, training, and direct actions against global warming.

“Clinicians need to be ready to deal with the changes in the infectious disease landscape,” said senior author George R. Thompson, a professor of medical microbiology and immunology at UC Davis. “Learning about the connection between climate change and disease behavior can help guide diagnoses, treatment and prevention of infectious diseases.” 

Infectious diseases are on the move

Thompson further advised medical practitioners to maintain “a high index of suspicion of diseases on the move,” suggesting that an enriched understanding of disease mechanisms could significantly improve testing and reduce the incidence of overlooked cases.

The scientists analyzed the shifting paradigms of infectious diseases, including those caused by viruses, bacteria, fungi, or parasites. These illnesses are often transmitted either from animals to humans or from person to person. 

Vector-borne diseases

Among these, the team singled out for discussion vector-borne diseases – illnesses propagated by carriers such as mosquitoes, fleas, and ticks. The diseases highlighted, including dengue, malaria, and Zika, represent a fraction of the broader spectrum of illnesses that are being exacerbated by climate change.

The study points to changing precipitation patterns and warming climates as key drivers expanding the geographical range and extending the activity periods of vectors. This phenomenon is resulting in a notable increase in vector-borne diseases, with conditions traditionally confined to warmer months, like those caused by ticks (e.g., babesiosis and Lyme disease), now manifesting in colder seasons and spreading to new regions.

“We’re seeing cases of tick-borne diseases in January and February. 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,” said lead author Matthew Phillips, an infectious diseases fellow at Massachusetts General Hospital and Harvard Medical School.

According to Phillips, another major threat is posed by malaria. “As an infectious disease clinician, one of the scariest things that happened last summer was the locally acquired cases of malaria. We saw cases in Texas and Florida and then all the way north in Maryland, which was really surprising. They happened to people who didn’t travel outside the U.S.”

Shifting patterns of zoonotic diseases 

Furthermore, the research underscores the shifting patterns of zoonotic diseases, like the plague and hantavirus, which are borne by rodents. Changes in animal migration patterns and habitat encroachments are bringing wild animals – and the diseases they carry – closer to human populations, increasing the risk of cross-species disease transmission.

Newly emerging fungal pathogens, such as Candida auris (C. auris), and the geographical spread of other fungal diseases like Coccidioides (or Valley fever) emphasize the unpredictable and dynamic nature of infectious diseases in the context of climate change.

Spread of waterborne diseases 

Adjustments in rainfall patterns and coastal water temperatures, coupled with rising sea levels and more frequent coastal flooding events, are similarly influencing the spread of waterborne diseases, such as those caused by E. coli and Vibrio, presenting additional challenges for public health.

“[These infectious diseases] can spring up and cause absolute chaos for the whole world and then we kind of forget about them for a while. Yet, the epidemic and pandemic potential of infections really mandates that we stay involved with federal funding agencies and advisory groups to make sure that infectious diseases don’t slip back too far on the public’s radar.”

Stronger infectious disease surveillance systems

Thus, the researchers advocate for stronger infectious disease surveillance systems, while urging medical educators to train clinicians to anticipate and more reliably identify the changes in infectious disease patterns.

“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 first-hand 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.

This collaborative effort highlights the urgency of a unified and informed response from the medical community to the challenges posed by climate change, advocating for an integrated approach that spans education, surveillance, and policy advocacy to safeguard public health against the backdrop of a warming planet.

The study is published in the journal JAMA.

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