Valley Fever

Valley fever is caused by fungi that live in the soil. (credit: UC David School of Medicine)

DAVIS, Calif. — Climate change is doing much more harm than raising temperatures to dangerous levels — researchers say it’s also spurring the spread of deadly infectious diseases. The new study by a team at the University of California-Davis School of Medicine is calling for increased awareness, preparedness, and action within the medical community to address emerging health threats caused by climate change.

Researchers are shedding light on the complex relationship between climate change and infectious diseases, emphasizing the need for clinicians to adapt swiftly to the evolving landscape.

“Clinicians need to be ready to deal with the changes in the infectious disease landscape,” says study lead author George Thompson, a professor at the UC Davis School of Medicine in the Department of Internal Medicine, Division of Infectious Diseases, and the Department of Medical Microbiology and Immunology, in a media release. “Learning about the connection between climate change and disease behavior can help guide diagnoses, treatment and prevention of infectious diseases.”

The article, published in the journal JAMA, draws attention to various infectious diseases — caused by viruses, bacteria, fungi, or parasites — and their transmission, either from animals to humans or from person to person. A particular focus is on vector-borne diseases like dengue, malaria, and Zika, which are transmitted by carriers such as mosquitoes, fleas, and ticks.

Tick Lyme Disease
(Credit: Erik Karits from Pexels)

How Is Climate Change A Catalyst For Disease Spread?

In the study, experts detail how shifting climate patterns, including changing rain patterns, shorter winters, and longer summers, are broadening the habitats and active periods of disease vectors. This has led to an increase in diseases such as babesiosis and Lyme disease, traditionally confined to specific seasons and regions, now occurring in new areas and times of the year.

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

The spread of malaria is also experiencing a northward shift, attributed to climate-induced changes affecting mosquito populations. The phenomenon of locally acquired malaria cases in regions like Texas, Florida, and even as far north as Maryland, as observed last summer, underscores the growing threat posed by climate change to public health.

The paper also discusses the risk associated with zoonotic diseases — infections transmitted from animals to humans. Changes in animal migration patterns and habitats, partly due to climate change, are increasing human exposure to potentially new and dangerous pathogens. Additionally, the emergence of new fungal infections and the expanded geographic reach of diseases like Valley fever are highlighted as signs of the changing disease landscape.

Acknowledging the global disruption caused by recent infectious disease outbreaks, such as COVID-19, the authors advocate for enhanced infectious disease surveillance and proactive measures to adapt medical education and training.

“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,” notes Phillips.

The study, funded by the National Institutes of Health, stresses the importance of ongoing engagement with federal funding agencies and advisory groups to ensure infectious diseases remain a priority in public health agendas.

StudyFinds’ Matt Higgins contributed to this report.

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