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Tick tock, tick season is coming. What you need to know.
Statewide Tick Surveillance
Anyone who spends time outdoors has likely encountered ticks and has read news articles discussing tickborne illnesses. You likely wondered how prevalent are ticks across the state, what is the risk to humans of tickborne illnesses, and what steps we can take to mitigate and prevent our 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 out of the University of Illinois’ Illinois Natural History Survey’s Medical Entomology Lab, to discuss ticks, tickborne illnesses, and prevention strategies.
Dr. Tuten is currently leading statewide tick surveillance at the INHS Medical Entomology Lab in partnership with the Illinois Dept. of Public Health. Their program, currently running through 2023, 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). Ticks are collected to better understand their geographic range and are tested for disease causing agents, such as bacteria or viruses. Results are shared by the Illinois Department of Public Health in publicly available maps hosted on their 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 they can 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 can be used to anticipate risks to human health.
Blacklegged Tick – This species is currently invading Illinois north to south. The INHS Medical Entomology Lab surveillance and the work of colleagues, such as Dr. Brian Allan, has shown 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 can be found 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 indicates 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.
Figure 1: Tick species and the pathogens they have tested positive for in Illinois. Click photo to enlarge.
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 find their next meal and their propensity to typically transfer off vegetation between 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 on 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 the label instructions before use and carefully follow. 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 worried about smell.
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 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 the idea that ticks still may 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.”
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 in the United States. The ability to clone itself does give 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 through the bite of a lonestar tick and would make 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 likely more of 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 instantaneously, 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 as to 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). Lonestar ticks were often thought of as just a nuisance because they do not carry the agent of Lyme, but now with 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.
Figure 2. Geographic distribution of alpha-gal IgE-positive persons per 100,000 population by state—United States, 2010 to 2018 (N = 15,091). Data are based on the state of origin of the first specimen testing positive for 15,091 persons. Number of persons tested and number of positive per 100,000 were calculated using the average US Census population by state during the study period. Legend categories were created using percentile distribution of data. Alpha-gal, galactose-alpha-1,3-galactose; IgE, immunoglobulin E; N/A, not applicable; No., number. Click photo to enlarge.
If you are interested in learning more about ticks, please watch the entire discussion with Dr. Holly Tuten here:
For more tick information please follow the links below:
Watch another Webinar Dr. Holly Tuten gave to the Champaign Co. Forest Preserve District where she discusses the IDPH maps and tick bite prevention here.
Lean more about the Medical Entomology Lab here.
For current Illinois tick-borne disease case numbers, please reference the IDPH website. State and national Lyme disease data can be found here.
Knowing how to properly remove a tick is VERY important. Do not try to burn, smother, twist, or crush the tick! This could cause the tick to regurgitate into you. Instead, please follow the CDC instructions here.
The Illinois Lyme Association provides a lot of additional information and support here.
Have a photo of a tick you want identified upload a photo to Tick Encounter here.
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