Eau Claire County study: More than 1 in 3 ticks could spread illness

Apr. 12—EAU CLAIRE — It's that time of year again when the temperature starts rising and Chippewa Valley residents spend more time outside.

While that's mostly a welcome development, it comes with a warning from public health officials: Beware of ticks.

A recent U.S. Centers for Disease Control and Prevention analysis shows that more than one in three ticks in two Eau Claire County parks have the possibility of spreading illness to people, with Lyme disease being the most common.

The results were from a study in which the Eau Claire City-County Health Department sent deer ticks collected in 2019 at Keller Park in Fall Creek and Coon Fork County Park near Augusta to the CDC to evaluate the presence of tickborne diseases in the area. The results were delayed by the COVID-19 pandemic.

In 2020, 34 cases of Lyme disease were reported in Eau Claire County, although the Health Department indicated the actual number was probably much higher because many cases go unreported.

"This study shows the importance of taking steps for insect bite prevention, like using an insect repellent to protect yourself and your family against ticks," said Savannah Bergman, a chemist-microbiologist with the Health Department.

Local studies using ticks collected from other Eau Claire County parks in previous years showed an even higher prevalence of ticks carrying Lyme and other diseases.

Overall, research shows Wisconsin and Minnesota, along with the Northeast, tend to have among the highest incidence of Lyme and other tickborne illnesses in the nation, and the rate is higher in northwestern Wisconsin than in the rest of the state.

The recent study showed that local ticks carry at least four other potentially serious tickborne diseases, with some ticks carrying more than one pathogen, Bergman said.

"The big message we want people to be aware of is that ticks in our area don't just have Lyme disease, even though that is the one people talk about the most," she said. "We definitely have quite a few tickborne diseases in our area."

Other illnesses identified in Eau Claire County ticks include anaplasmosis, babesiosis, borrelia miyamotoi and ehrlichiosis. Anaplasmosis has the potential to be fatal when people don't catch it, and health outcomes tend to be worse for people infected with multiple tickborne diseases, said Susan Paskewitz, an entomologist at UW-Madison.

"The more awareness people have about the potential for multiple pathogens, the better they can advocate for their own health," Paskewitz said.

This is about the time of year when adult ticks typically become active, Paskewitz said, adding, "People already are seeing them on their dogs and themselves, so we've just got to keep doing those tick checks."

The highest-risk season is generally June through mid-July, when deer tick nymphs are most active, she said.

Most tickborne diseases in Wisconsin are spread by the deer tick, also known as the black-legged tick, which is smaller than other ticks and reddish to dark brown in appearance.

Other ticks found in the Chippewa Valley are the extremely common wood, or dog, ticks, which have whitish markings and can spread Rocky Mountain spotted fever but rarely transmit disease in Wisconsin, and the less common Lone Star ticks, which have a white dot on their back and can spread ehrlichiosis.

Dog ticks are often found in grassy areas, while deer ticks are more plentiful in wooded areas.

Symptoms of illnesses spread by ticks can range from mild to severe and can include fever, chills, sweats, rash, muscle aches, joint pain, headache, fatigue, nausea and vomiting.

"I think most people have heard hard stories of people who didn't take tick warnings seriously or who have longer-term impacts from being infected," Paskewitz said. "Why not take time to do a little prevention? Who wants to get sick?"

Paskewitz was co-author of a recently released study highlighting a prevention measure homeowners can take to reduce their chances of tick exposure in their own yards. The study, which collected tick data from the backyards of 51 volunteers from Eau Claire and Altoona and 39 from Reedsburg in June 2019, tested the effectiveness of applying a relatively low-cost pesticide for control of ticks in lawns that were adjacent to wooded areas.

The research showed that properties that treated the strip of lawn closest to the woods with a granular form of gamma-cyhalothrin reduced nymphal deer ticks by 97% in the week after the application and by 89-97% after three to four weeks.