Rising Tick Bite Cases Linked to Climate Change

This year has seen a notable uptick in emergency care for tick bites, reaching levels not seen since 2017. According to the US Centers for Disease Control and Prevention, reported instances of Lyme disease are also on the rise.

Experts attribute these increases largely to climate change and warmer temperatures, which allow ticks to spread into areas of the US and Canada where people might not be familiar with the associated risks and how to mitigate them.

Dr. Thomas Daniels, who directs the Louis Calder Center at Fordham University, noted that when Lyme disease research began in the mid-1980s, cases in Canada were quite rare. Today, Lyme disease is well established throughout the country.

Tick species that carry Lyme disease thrive in temperatures above 45°F and prefer environments with high humidity—around 85%—as indicated by the US Environmental Protection Agency.

“Ticks prefer humid areas, not soggy ones,” Daniels said. “If you check a sun-baked lawn, the chances of finding ticks are low. But go a little into the woods, where it’s shady and cooler, and you’ll likely encounter them.”

As the climate continues to change, the risks from ticks and other vectors like mosquitoes—responsible for diseases such as West Nile, dengue, and malaria—are also escalating.

Dr. Erin Mordecai, an associate biology professor at Stanford, mentioned at a recent briefing that rising temperatures have made conditions more favorable for disease transmission in North America.

While climate change is a significant factor in the expansion of tick habitats, it’s not the only one. Human alterations to landscapes also play a role.

Dr. Jean Tsao, a Michigan State University professor who researches disease ecology, commented, “It’s not just one cause, right? In the continental US, much of the spread is likely linked to land use changes involving wildlife communities, along with wildlife population management like that of white-tailed deer.”

Deer ticks, or black-legged ticks, are the primary carriers of Lyme disease. At their nymph stage, they’re about the size of a poppy seed and easily overlooked. While feeding, these ticks can transmit pathogens such as the bacterium Borrelia burgdorferi, which causes Lyme disease.

According to Brian Fallon, director of the Lyme and Tick-Borne Diseases Research Center at Columbia University, the infection may trigger a variety of symptoms affecting multiple systems in the body, including the heart and central nervous system.

The onset of Lyme disease can manifest diversely. Fallon pointed out that while many associate Lyme with a specific bullseye rash, that’s not typically what appears first. Often, it starts as a pinkish or reddish rash that expands significantly.

He also noted that individuals may develop multiple rashes across their body. Without treatment, more severe symptoms can emerge, potentially lasting for months or even years.

“Early symptoms are often recognized through a rash, if it’s spotted—later, neurological symptoms might develop, presenting as facial paralysis or severe headaches,” Fallon explained. “Cardiac issues like palpitations can occur too, along with muscle pain and fatigue. It can be very debilitating.”

Daniels highlighted precautions people can take to lessen the risk of tick bites, though he admitted methods aren’t entirely foolproof. Timely tick removal is crucial, he emphasized.

“Getting a tick off as quickly as possible is key. Most pathogens aren’t transmitted rapidly, except for Powassan virus, which can be spread in about 15 minutes, albeit its infection rate is quite low. For Lyme disease, you generally have 24 to 48 hours to remove the tick before it transmits the bacteria,” Daniels noted.

He suggests wearing more clothing during the summer months. “Keeping ticks on the outside reduces the chance of them finding skin to attach to. And treating clothes with permethrin can also help repel ticks.”

During hikes, both Daniels and Fallon advised sticking to trails, as ticks are often found in leaf cover or wood piles. They also recommend conducting thorough “tick checks” on each other when in tick-infested areas.

“Ticks can find their way to tricky spots like behind your knees or on your back, which can be hard to see or reach,” Fallon said. “Taking a shower at the end of the day may help wash away any ticks that haven’t attached completely.”

If a tick remains attached, Fallon warns it can swell significantly from sucking blood, eventually becoming as large as a raisin. He advises using tweezers to safely remove the tick from its body.

“Avoid methods like burning it off or applying toxic substances. Just use tweezers,” he concluded.