How Climate Change is Contributing to the Spread of Vector-Borne Illnesses — and How to Protect Yourself

Ticks, mosquitoes, and fleas have long served as vectors that can transmit pathogens to humans. Some of the best-known vector-borne diseases around the world include malaria, dengue, chikungunya, yellow fever, and Zika. (Evidence suggests the virus causing COVID-19 likely jumped to humans from an animal host.)

In the United States, the list also includes Lyme disease (caused by Borrelia burgdorferi or Borrelia mayonii, types of bacteria carried by black-legged ticks) and West Nile virus (transmitted by mosquitoes).

More than half of all the infections that people can get are zoonotic, meaning they go from animals to people.

“According to the CDC, more than half of all the infections that people can get are zoonotic, meaning they go from animals to people,” says Rountree. Changing weather patterns, expanding human development, and waning biodiversity all increase the odds that more of us will encounter these kinds of infections more often.

“The risk of Lyme disease is going to go higher and higher because of degraded habitats,” he explains. “In a healthy habitat, you have a lot of natural predators that feed on the mice that carry the ticks that transmit Lyme. When you fragment the forest, you lose those predators and the mice become more prevalent. Then you go for a fun hike and boom, you get exposed to Lyme and other tick-borne diseases.”

Higher temperatures are expanding the range where disease-carrying mosquitoes and ticks can live and reproduce. “Where winters have historically been protective, vectors are now able to hang around longer, reproduce longer, and spread ­disease longer,” Lemery says. “Diseases that have long been the domain of tropical and subtropical areas are moving slowly into higher latitudes and altitudes.”

How to Build Resilience

Prevention is the best strategy when addressing vector-borne diseases. “Since black-legged ticks are the main carriers of the bacteria that cause Lyme and related diseases, the best way to prevent Lyme is not to get bitten in the first place,” says Rountree.

He notes that this can be challenging: The biggest offenders are small, immature ticks called nymphs, less than 2 millimeters in size and hard to see. He emphasizes the importance of using good bug repellents and conducting a thorough skin check after hiking. When you’re in tick-friendly habitats, such as dense woods, forests, and prairies with tall grass, wear some tick-protective clothing. (For more tips on avoiding ticks, see “Lyme Disease: How to Protect Yourself This Summer.“)

Vaccines may also play an increas­ing role in fighting zoonotic infections. A new malaria vaccine, developed by scientists at the University of Oxford, was recently found to be up to 80 percent effective in clinical trials; it is expected to be rolled out across sub-Saharan Africa this year.

A vaccine against Lyme disease is currently in stage 3 clinical trials, and a monoclonal-antibody treatment for the disease is also in the works.

Still, the growing range of Lyme-prone areas means that more healthcare providers need to learn how to recognize and treat it, Lemery says. “Lyme is an insidious disease — a great mimicker that can hide below the surface. We’ll need to recalibrate our healthcare systems to be ready to treat these types of diseases that maybe historically haven’t been an ­issue.” (Learn more about new treatments for Lyme at “A New Look at Chronic Lyme.”)

Following an overall immune-supportive diet and lifestyle remains important on the individual level, too. Maintain a vitamin D status in a functional range (50–80 ng/mL) and ensure you’re getting enough zinc, omega-3 fatty acids, and vitamins A and C. These help the body fight infections and, crucially, resolve them, Purdy says. (To learn how to make your meals more immune ­supportive and climate friendly, see “Eat a Climate-Friendly Diet” further down.)

“Your body needs the team of soldiers to fight the infection, but also the team of architects and construction workers to rebuild and maintain the integrity of the immune system so it’s ready for the next infection it comes across,” Purdy says. “So often we’re stuck with this immune system on high alert, and we need some of those food compounds to help calm it down again.” (Find out how to support the immune system at “How Chronic Inflammation Affects Your Health.”)

This was excerpted from “How Climate Change Affects Your Health — and How to Build Resilience” which was published in Experience Life magazine.