Anyone who spends time outdoors has likely encountered ticks and has read about tick-borne illnesses. You likely wonder how prevalent ticks are across the state, what the risk is to humans of tick-borne illnesses, and what steps we can take to mitigate and prevent interactions with ticks. Today, we hope to provide some answers to these questions. Recently, we sat down and talked with Dr. Holly Tuten, a vector ecologist working at the University of Illinois Illinois Natural History Survey Medical Entomology Lab, to discuss ticks, tick-borne illnesses, and prevention strategies.
Statewide Tick Surveillance
Dr. Tuten is currently leading statewide tick surveillance at the INHS Medical Entomology Lab in partnership with the Illinois Department of Public Health. Their program, currently running through 2026, has several surveillance targets: the American dog tick (Dermacentor variabilis), the blacklegged tick, aka “Deer tick” (Ixodes scapularis), the Gulf Coast tick (Amblyomma maculatum), and the lone star tick (Amblyomma americanum). The lab collects ticks to better understand their geographic range and tests them for disease-causing agents, such as bacteria or viruses. Results are shared by the Illinois Department of Public Health in publicly available tick maps (hosted on the IDPH website). As surveillance data is compiled, they discuss risk awareness for hikers and hunters. For now, the primary objective is finding and testing as many ticks as possible to better understand species prevalence across Illinois.
Species Distribution
Understanding a species’ distribution is critically important since the pathogens that they may carry are species-specific. Essentially, species distribution data can be used to anticipate risks to human health.
Blacklegged Tick – This species is currently invading Illinois from north to south. The INHS Medical Entomology Lab surveillance and the work of colleagues, such as Dr. Brian Allan, have shown the highest tick density in northern Illinois, but it can be found across the state.
Lone Star Tick – On the flipside, the INHS-MEL surveillance indicates that the lone star tick is most dense in southern Illinois and expanding its range north. The leading edge of expansion appears to be in central Illinois, but it is reported throughout the state.
American Dog Tick – The American dog tick is prevalent in Illinois and can be found across the state.
Gulf Coast Tick — Current results from the INHS Medical Entomology Lab surveillance program indicate that the Gulf Coast tick is established in several southern IL counties, but it remains to be seen if they will move further north.
Disease Prevalence in Illinois Ticks
As we mentioned earlier, the INHS-MEL surveillance highlights the general prevalence of pathogens across the state. To date, the blacklegged tick has been sampled across northern and central parts of the state, and 39% of ticks tested positive for the agent of Lyme disease, but the likelihood of the disease agent varies by location, with more positive ticks in northern Illinois. According to the testing data collected thus far, the lone star tick carries agents of Ehrlichiosis at a rate of 2% to 3% and the American dog tick carries the agent of Rocky Mountain Spotted Fever (RMSF) at a rate of 1% to 2%. The Gulf Coast tick transmits Rickettsia parkeri, which is a spotted fever agent related to RMSF. INHS-MEL testing revealed a Rickettsia parkeri prevalence as high as 50% in some areas, with an average of 17%. Tuten stated: “To see something as high as 50% prevalence, it is different, it is shocking.”
These results indicate that it is possible, if not likely in some instances, to come across an infected tick while out in the Illinois woods hunting, scouting, hiking, or just spending time outdoors. This research highlights the importance of preventative steps that individuals should take while spending time in areas where ticks may be present.
Tick Prevention Tips: “Don’t be scared; be prepared”
Dr. Tuten explained that a generalization of how ticks find their meal is through the detection of movement, body heat, and CO2 sensing. Knowing how ticks hunt and their propensity to typically transfer from vegetation to ankles and thighs and then climb up, it is possible to prevent tick bites when in the field. Holly says, “Don’t be scared; be prepared.”
Tips for prevention in the field
- Make an ascending clothing barrier.
- Ticks typically transfer at thigh level and below, will stereotypically crawl up, so have an ascending barrier with your clothes. Having your pants tucked into your socks and your shirt tucked into your pants will prevent them from crawling up and under your pant cuff or shirt.
- Use EPA-approved permethrin insecticide.
- You can buy clothing that is pretreated or treat your own clothing. Read and carefully follow the label instructions before use. Note that the container states that it is highly toxic to cats when wet.
- Once clothes are treated, the spray will be effective for several washes and is odorless, making it great for hunters who worry about fragrances.
- Permethrin creates a symptom called “hot foot” in ticks. When they climb onto the fabric, the tick cannot stand to be on the clothing anymore and will fall off.
- Use EPA-approved repellent.
- EPA-approved repellents, like DEET, will repel ticks from climbing onto your clothing.
- Read the label instructions before use and carefully follow.
- Walk in the middle of the trails.
- Stay in the middle of the trail or in open woods to prevent brushing up against vegetation.
- Occasionally, perform visual tick checks of boots, bags, and clothing while in the field.
Once you return home
- Undress next to the washer and dryer to prevent ticks from falling off around your house.
- High heat kills ticks, not water, so at least dry your clothes, with longer dry times for damp clothing.
- Take a shower to wash off any unattached ticks. According to the CDC: “Showering within two hours of coming indoors has been shown to reduce your risk of getting Lyme disease and may be effective in reducing the risk of other tickborne diseases.”
- Perform a tick check: look and feel for any ticks.
Another significant issue that hunters need to be cognizant of is that ticks may still be attached to a harvested carcass and may leave the carcass during transportation or when at home before processing. This could cause ticks to remain in your car, hunting pack, etc. IL Learn to Hunt can recommend a few steps that hunters can take to ensure that they are not susceptible to ticks from a harvested carcass.
- For small game (e.g., squirrels, rabbits), you can place the harvested game inside a Ziploc bag before placing in your game vest or hunting pack.
- For larger game like deer, be very cautious about transporting deer in the cab of a vehicle or in a trunk. Again, read and follow the instructions, but it can be safe to treat the fabric parts of your car with permethrin or to use a permethrin-treated blanket to lay the carcass on during transport.
If you hang a deer carcass in your garage before processing, over time, you will notice ticks falling off the carcass. Many recommend placing a permethrin-treated sheet under the hanging carcass. Ticks that fall off the carcass will fall onto the sheet and die, reducing the likelihood of them living in your garage.
Emerging Issues
“If you thought ticks were awful, they have just gotten more awful.”
— Holly Tuten, Ph.D., vector ecologist
A New Clone Invader
The expression “be careful what you wish for” does not stop at magical genies; it also applies to interviews with vector ecologists. We found that out the hard way when we asked Dr. Tuten if she had any “additional facts” about ticks to share. Tuten went on to explain that a new invasive species of tick, the Asian longhorned tick (Haemaphysalis longicornis), currently found as close to us as Ohio and Kentucky, has a surprising ability. This tick can reproduce through parthenogenesis. This means that the female tick no longer needs a male tick to reproduce because it can clone itself. “If you thought ticks were awful, they have just gotten more awful,” Tuten said. The good news is that while the Asian longhorned tick has been associated with some human diseases in its home range, it has not yet been captured in the United States. The ability to clone itself gives this tick a high potential to establish itself in new areas, and it still may become associated with diseases as its population becomes more established.
Alpha gal: Mammal Meat Allergy
Dr. Tuten went on to describe another fact that could be VERY impactful to hunters. Tuten described the Alpha-gal allergy. This allergy can be caused by the bite of a Lone Star tick and makes the affected person allergic to mammal meat and mammal byproducts. This can be hard to clinically recognize in some cases, since the tick does not transmit anything (e.g., a pathogen); it is more likely a reaction to something within the gut of the tick. There is a delay after the initial tick bite, and you may not feel adverse effects until consuming meat several weeks later.
Unlike a peanut allergy, which can cause issues immediately, you may have a delayed anaphylactic reaction several hours later as your body digests the meat. In some people, it never proceeds to anaphylaxis but presents with gastrointestinal distress. With these delays, it may not be clear to clinical diagnosticians what is causing the illness, but there is a human test for the allergy. The only real option for people with this condition is to stop eating mammalian meat; however, some people have gone into remission. Illinois is one of seven states in the US with the 2nd highest occurrence of this allergy. Nearby states, like Missouri and Arkansas, have some of the highest rates in the country (see Fig. 2 below — Binder et al. 2021). Lone Star ticks were often thought to be just a nuisance because they do not carry the Lyme agent, but now that we know about this allergy, more people should be aware of their existence.
So, as Dr. Tuten said, “Don’t be scared; be prepared!” and take the necessary precautions to ensure you have a safe and successful time afield.
If you are interested in learning more about ticks, you can watch the entire discussion with Dr. Holly Tuten here:
More Resources
- Watch another webinar Dr. Holly Tuten gave to the Champaign Co. Forest Preserve District, where she discusses the IDPH maps and tick bite prevention.
- Lean more about the INHS Medical Entomology Lab.
- For current Illinois tick-borne disease case numbers, please reference the IDPH website. The CDC also tracks state and national Lyme disease data.
- Knowing how to remove a tick properly is VERY important. Do not try to burn, smother, twist, or crush the tick! This could cause the tick to regurgitate into you.
- The Illinois Lyme Association provides a lot of additional information and support.
- Have a photo of a tick you want identified? Upload a photo to Tick Encounter.
Citation
Binder, A. M., Commins, S. P., Altrich, M. L., Wachs, T., Biggerstaff, B. J., Beard, C. B., Petersen, M. D., Kersh, G. J., Armstrong, P. A. (2021). Diagnostic testing for galactose-alpha-1,3-galactose, United States, 2010 to 2018. Annals of Allergy, Asthma & Immunology. doi:10.1016/j.anai.2020.12.019