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Emergency room visits for tick bites reached a nine-year high across much of the U.S. this spring.
In April, tick bites accounted for more than 100 of every 100,000 emergency department visits — a jump from 68 of every 100,000 visits last year, according to the U.S. Centers for Disease Control and Prevention. Many of those visits were in the Midwest.
Ticks have become more active throughout the year due to milder and shorter winters. There’s also evidence pointing to an increase in the number of ticks in some areas.
For example, the LaSalle County Health Department in northern Illinois collected more ticks during a "tick drag" than at any other time to date. Tick drags are a survey method that involves dragging a light-colored cloth along the ground and collecting any ticks that attach themselves to it.
Ram Raghavan is an associate professor at the University of Missouri College of Veterinary Medicine. He collects and studies ticks throughout the Midwest.
He said he used to go out to collect ticks starting in mid-April until mid-August, but now he can find ticks from mid-March to early October. He said the risk of encountering a tick is never actually zero even through the winter. If it’s warm enough, they will be active.
“Because the seasons are expanding on either side of the spectrum, you now are seeing an overlapping of different life stages,” he said. “You're also seeing potential chances for those ticks to transmit the pathogens they carry among themselves and also to the wildlife hosts.”
He said El Niño weather conditions ten years ago caused mild enough winters for ticks to emerge and become active earlier in the year. He said that’s expected to be the case again this winter.
“When it feels spring-like in the middle of winter, ticks will start emerging,” he said. “Increasingly, we are seeing that sort of phenomena happening. When the temperatures during the wintertime are warm enough for the ticks to emerge, they will emerge.”
But ticks can survive colder environments, according to Jonathan Cammack, an entomology extension specialist with Oklahoma State University. He said even a harsh winter doesn't do much to knock their populations back.
“Warmer winters will definitely increase their survival,” Cammack said. “In a normal winter, we would certainly expect some to die, because they are going to freeze, but they've evolved to be able to withstand these seasonal fluctuations.”
Raghavan said the climate is changing, and humans need to start adapting to that reality.
How ticks make people sick
Different tick species are more abundant in different parts of the country. East of the Rocky Mountains, the American dog tick and the blacklegged tick – often called a deer tick – are some of the most common species. The lone star tick is also prevalent in the Midwest and the eastern U.S. These three tick species combined can transmit more than 10 illnesses, including Rocky Mountain spotted fever, Lyme disease, Powassan virus and tularemia.
Lyme disease is the most common and affects about 476,000 people in the U.S. each year, according to the CDC. There’s also a growing number of cases of alpha-gal syndrome, an allergy to red meat that can develop after a bite from certain ticks — usually a lone star tick.
Ticks live for about three years, and they require blood meals at every one of their life stages. When they first hatch from an egg, they latch onto a small animal like a mouse or lizard, where they can potentially pick up a virus or pathogen. As they progress to later life stages, ticks seek out larger animals to feed on. Cammack with Oklahoma State University said that’s how diseases can transfer to humans.
“If all the stars happen to align and you get bit by the right life stage of a tick that's got the right life stage of that pathogen in it, then you could potentially become sick,” he said.
Sonja Swiger is an entomologist at the Texas A&M Agrilife Extension Service with an expertise in livestock. She spends much of her time presenting to livestock producers and the general public, and she said one of the most common misconceptions she hears is that ticks aren’t a major problem in Texas. But she said that is not the case.
“While most of the pathogens we deal with from ticks in the United States at this time do not technically cause illness in our cattle, the presence of those ticks could lead to an impact to their health,” she said. “It's not just protection of the animals you're looking at, you're also protecting yourself from being bitten by those ticks as well.”
Swiger said that she’s encountering more people who are aware of ticks and the risk they pose to human health.
“We're definitely seeing a gained interest in ticks and tick-borne diseases,” she said. “Nationwide, there's been a huge increase in tick-borne disease transmission in the last couple years, almost three or four times as much as we have been seeing prior to that.”
There are multiple efforts throughout the U.S. to track tick species and tick-borne illnesses. Several states, including Illinois, Indiana, Wisconsin, Michigan and Texas, have citizen science programs, where people can submit ticks to be identified and tested for pathogens.
A recent citizen science study out of Wisconsin found about half of deer ticks tested in the state carried bacteria that could become Lyme disease.
'It's just better to be cautious'
Teresa Steckler works with the Illinois Natural History Survey and University of Illinois Medical Entomology Lab to track the movement of Theileria, a disease affecting cattle that comes from a longhorn tick bite. Longhorn ticks only showed up in Illinois two years ago, making it the 20th state to find the species.
She said it’s best to take precautions to protect yourself from tick bites.
“I just tell everyone to be cautious about any and all ticks,” Steckler said. “That's not to say that all ticks are harboring disease-causing agents. They are not. But it's just better to be cautious than to be dismissive of having a tick on you and having a tick bite.”
She recommends avoiding wooded or grassy areas where ticks may be or treating clothing with the insecticide permethrin to guard against them.
Steckler also said to check yourself and your pets thoroughly for ticks any time you come inside from where ticks may be.
If you find a tick, carefully pull it off with tweezers and store it in a bag in the freezer in case you develop any flu-like symptoms or a rash. Steckler said you can bring it with you to the doctor to be tested for pathogens.
This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest and Great Plains. It reports on food systems, agriculture and rural issues.
