Ticks on the rise in Illinois due to milder winters, scientists say

Illinois’ tick season may be starting earlier, lasting longer and creeping into new corners of the state, scientists and researchers say.

Milder winters and earlier springs are helping ticks survive in greater numbers, while doctors report earlier cases of tick-borne illnesses this year than in previous seasons. And ticks aren’t only in heavily forested areas. More and more, experts say, ticks are also being found in city parks, green spaces and suburban yards.

“It’s not true that ticks are only something you’re going to encounter on a camping trip. Increasingly, that’s simply not true. Ticks don’t recognize city limits,” said Dr. Kelly Cairns, president of the Chicago Veterinary Medical Association.

Tick season usually spans April through September. But all four seasons have seen warmer temperatures because of human-driven climate change, and winter temperatures have increased at a much faster rate than all other seasons, experts say.

Shorter winters have led to the expansion of tick populations, a trend that is most prevalent in the Midwest and Northeast.

“With climate change, it seems like ticks are able to survive better and get active earlier than what we would usually see,” said Patrick Irwin, lead entomologist with the Northwest Mosquito Abatement District, a government agency that monitors and controls mosquito, fly and tick populations in northwest Cook County.

Ticks go dormant in temperatures below 40 degrees, hibernating beneath leaf litter and snow. They begin to die off when temperatures drop below 14 degrees. This year’s cold snaps, Irwin said, were accompanied by snow, which insulated the ticks from the full effects of the cold.

February, March and April were also above average in temperature, allowing ticks to emerge from hibernation earlier.

This spring, the Northwest Mosquito Abatement District recorded a nearly sevenfold increase in deer tick sightings compared with last year, Irwin said. He said his team is conducting more “tick drags” — where researchers drag a white cloth through an area to collect ticks — in the suburbs.

Tick bites occurring earlier

Ann Miller, a Jefferson Park school social worker, said she found a tick on her mini Bernedoodle dog, Millie, last year. She believes the bite may have happened on a visit to her mother’s house in Crystal Lake.

Millie tested positive for Lyme disease but, after bloodwork, a veterinarian decided she didn’t need antibiotics and could fight off the infection on her own. In May, Miller said, Millie began displaying “strange” symptoms.

“She started randomly limping on one paw, then the next day she would limp on another paw,” Miller said. “She didn’t want to get out of bed; she didn’t want to eat her food. She would run very quickly to a spot and sit down, and not want to move from there.”

Further tests showed that Millie had an active case of Lyme disease. After a few days on the antibiotic doxycycline, Miller said, the symptoms subsided.

Miller said she was aware of ticks but didn’t realize how early in the season bites could occur.

“She was at my mom’s house probably at the end of April, and I didn’t really think about starting the flea and tick medicine that early. I thought of it more as something for later in the summer,” Miller said.

“This year, we started her tick medication much earlier than we had done the year before,” she added.

According to Cairns, the veterinarian, the best way to protect pets from tick bites is through preventative medication and tick checks after outdoor activities.

“If you know your dog has had a tick on it, please call your vet. It’s not something that you want to wait on,” Cairns said.

A ‘life-altering’ diagnosis

Ticks latch onto hosts through a process called “questing.” The arachnids sit and wait in vegetation, like tall grass and weeds, with their legs outstretched to cling onto any host that brushes by. They thrive in shaded, slightly humid environments, like piles of leaves.

Ticks can feed on a host’s blood for days. While doing so, they may transmit bacteria like the one that causes Lyme disease. And because ticks can be as small as a poppy seed, they often go unnoticed.

The Illinois Department of Public Health usually reports around 300 confirmed cases of Lyme disease per year. But because many patients don’t recall being bitten by a tick and many early symptoms mirror the flu, there are likely many more cases that go unreported.

According to the IDPH, those numbers are also rising, with Illinois seeing a long-term increase in cases of tick-borne disease. Nationally, the Centers for Disease Control and Prevention reported “higher than normal” visits to the emergency room for bites this April.

Across the country, except for Texas, New Mexico, Oklahoma, Arkansas and Louisiana, weekly rates of emergency-room visits for tick bites were the highest for that time of year since 2017.

St. Charles resident Laura Sislow said she began noticing flu-like symptoms 21 years ago, although it took nearly a decade for her to be diagnosed with Lyme disease. She’s still unsure when or where she was bitten.

“It turned into this crushing fatigue that was, and still is, not really fixed by sleeping,” she said.

When left untreated, Lyme disease can lead to lingering issues like brain fog, joint pain and arthritis. According to the CDC, the cause for these prolonged symptoms is currently unknown.

Lyme disease was “life-altering,” Sislow, 44, said, and she had to leave her “dream career” as a middle school counselor because of the illness.

“You feel like a shell of yourself because you’re not able to do the things that you used to be able to do,” she said. “You’re not able to do the things you so badly want to do.”

Public health guidance for tick bites mostly focuses on prevention: wearing protective clothing, using repellent and performing tick checks after outdoor activity.

“The best way to avoid tick-borne illnesses is to prevent tick bites in general and to prevent ticks from getting on you,” said Dr. Ihab Ahmed, an infectious disease physician at Northwestern Medicine. “There’s no antibiotic for that.”

He recommends dressing in light-colored clothing, tucking pants into socks and even using tape to prevent ticks from getting in.

“It’s not fashionable, but the best way to not get bit is to kind of look like a dork,” he said.