This story was first published on June 5, 2020
Update: Lyme disease is still a risk in the fall. Adult ticks, which appear around mid-October, are still very active as long as the temperature is above 40 degrees — below freezing weather doesn’t kill them, they just go dormant. People should be especially careful near leaf litter, where ticks take refuge.
People in cities have been relying on parks to get them through the coronavirus pandemic, but ticks infected with the bacteria that causes Lyme disease present another health risk, even in urban areas.
Thomas Simmons and his biology students from Indiana University of Pennsylvania collected blacklegged tick samples from random sites in four of the large Pittsburgh parks in 2015 and 2016–Schenley, Frick, Highland and Riverview Parks.
Listen to the story:
Overall, the team collected about 500 nymphs, and 200 adult ticks. Nymphs are the lifestage between larvae and adult ticks.
“Most cases of Lyme disease are due to exposure to nymphs,” Simmons said, “because they’re very small and people are outside this time of year and more likely to come in contact and not even realize they’ve been bitten.”
Simmons’ team used pieces of white flannel cloth to “drag” 100 meter sections of vegetation along the edges of trails and recreational areas to collect the adult ticks and nymphs. They also set up study plots within the woods, where nymphs prefer the cooler, moist habitat.
The ticks were taken back to a lab, and their DNA was analyzed for the Borrelia burgdorferi bacteria which causes Lyme disease.
The study was published first online in the Journal of Medical Entomology last September.
“It’s a wakeup call, and emphasizes the importance of looking at…Lyme disease risk in city parks in any place in the country.”
Ticks in Pittsburgh Parks
Overall, 50 percent of adult ticks, and 20 percent of nymphs are infected with the bacteria. Fewer infected ticks were found in Frick Park, and Highland Park had the most infected ticks. Researchers don’t know why.
This infection rate compares to areas of the country where Lyme disease has been a problem for decades, like the Hudson Valley in New York.
Simmons says the risk of contracting Lyme disease also depends on the density of ticks in an area. The study of Pittsburgh parks shows tick density as high as other endemic regions, and areas which are rural and suburban. In the Pittsburgh parks, the density is estimated to be about one tick per 2 square yards.
Simmon said the study on ticks in Pittsburgh parks is one of only two that he knows of which look closely at Lyme disease risk and ticks in urban parks.
“Not only is it useful and important for Pittsburghers to know that there is Lyme disease risk, and they should take precautions, as they should in rural and suburban parks, and in their backyards,” Simmons said. “But it’s sort of a wakeup call, and emphasizes the importance of looking at tick-borne disease risk, Lyme disease risk, in city parks in any place in the country.”
- Mid to late June is peak season for nymphs looking for hosts to feed on.
- While blacklegged ticks are often called deer ticks, because ticks like to feed on them and deer can help spread the ticks geographically because of their range, deer don’t actually carry the Lyme disease pathogen.
- White-footed mice and other wildlife in wooded areas transmit the bacteria back and forth with blacklegged ticks.
- Not every bite by an infected tick will result in Lyme disease.
- If you find a tick on your clothes, or remove one from your body, you can have it tested for the bacteria that causes Lyme disease for free at East Stroudsburg University.
Protecting yourself from tick bites:
- Stay to the center of trails, and away from edges where ticks
- Wear light-colored clothing so that you can see ticks clinging to your pants and shirt. Tuck long pants into socks.
- Treat your clothing with an insecticide like permethrin, or with essential oils that repel ticks.
- When you go home from being outdoors, toss your clothes into a hot dryer for 10 to 15 minutes. Ticks cannot tolerate high temperatures.
- That day or that night, take a shower and check every part of your body to be sure that a tick has not embedded. It feels like a pimple or small bump or pimple.