Climate change in Pa. is increasing risk of Lyme disease, other tick-borne illnesses

Lyme disease can cause a raft of medical issues, including facial palsy, severe neck and headaches, and arthritis.

Sarah Boden/WESA

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Sarah Boden covers health, science and technology for 90.5 WESA. Before coming to Pittsburgh in November 2017, she was a reporter for Iowa Public Radio where she covered a range of issues, including the 2016 Iowa Caucuses.

Sarah’s reporting has appeared on NPR’s Morning Edition, All Things Considered, Weekend Edition Saturday and WBUR's Here and Now. She has won multiple awards, including a regional Edward R. Murrow for her story on a legal challenge to Iowa's felon voting ban.

FILE - This undated photo provided by the U.S. Centers for Disease Control and Prevention (CDC) shows a blacklegged tick, which is also known as a deer tick. Ticks will be more active than usual early in spring 2023, and that means Lyme disease and other tick-borne infections could spread earlier and in greater numbers than in a typical year. Ticks can transmit multiple diseases that sicken humans, and deer ticks, which spread Lyme, are a day-to-day fact of life in the warm months in New England and the Midwest. (CDC via AP, File)

June 30, 2023 | 10:48 AM

Pennsylvania has one of the highest rates of Lyme disease in the U.S., and the Allegheny County Health Department reports that roughly 30% of the blacklegged ticks that are active in the spring and early summer are carriers of this vector-borne illness.

At this time of year, blacklegged ticks have molted from the larval to nymph stages, and must consume a so-called “blood meal” to survive into adulthood. After feeding on its host, a nymph will swell to five or six times its original size.

Before their meal, nymphal ticks are the size of a poppy seed, making them hard to detect, explains Nick Baldauf, the vector control specialist for the Allegheny County Health Department. When checking for ticks, a person should look over their body thoroughly, including their waist, groin and neck, behind the ear – even under the armpit.

“It’s very important to be vigilant in taking precautions when you’re out hiking, enjoying the outdoors, doing things like, wearing permethrin products,” he said.

A picture taken at the French National Institute of Agricultural Research (INRA) in Maison-Alfort, on July 20, 2016 shows a tick, whose bite can transmit the Lyme disease. (Photo by BERTRAND GUAY / AFP)

It’s also a good idea to shower after being outdoors.

Lyme disease can cause a raft of medical issues, including facial palsy, severe neck and headaches, and arthritis. The Centers for Disease Control and Prevention says that after a tick attaches to a host, it usually takes 36 to 48 before the Lyme disease bacterium can be transmitted.

Research suggests that climate change is increasing the risk of Lyme disease in Pennsylvania, according to Emily Struckhoff, the vector-borne disease program specialist at Penn State Extension. Warmer weather extends the time a tick has to search for a host.

“Like this past winter, where we have some really warm winter days, where it gets about 40 degrees, those ticks can be active during times of year when we usually wouldn’t expect there to be ticks out and about,” she said.

Another impact of climate change: tick species from other parts of the U.S. are spreading, and with them new illnesses.

A bite from the lone star tick can transfer a sugar molecule to the human host. This can trigger Alpha-gal syndrome, which causes people to have an allergic reaction to mammal meat, such as beef or pork, along with milk and other dairy products. The Gulf Coast tick carries the bacteria that causes Tidewater spotted fever; symptoms include fever, muscle aches and a dry, dark scab over the tick bite.

As their names imply, both species are usually found further south, though their range has grown. So far this year, they’ve only been identified in Southeastern Pennsylvania.