Why Are We Seeing More Ticks in Chicago?



Ticks – Not Just In the Woods Anymore

Experts predict that the tick population and the diseases they carry will continue to be more and more prevalent in our area.  Why?  While more temperate weather has provided conditions for ticks to be active for more months of the year and to grow in their habitats, there’s another big reason.  According to Dr. Susan Little, a veterinary parasitologist at Oklahoma State University, that reason is the increasing mouse population.

Immature black-legged ticks (AKA “deer ticks”), responsible for transmitting the bacteria that causes Lyme disease, prefer mice as hosts. (In their adult phase, black-legged ticks prefer deer as hosts, thus their nickname.)  Deforestation and reforestation over the last century created the forest fragmentation we see today.  These fragmented forest areas have significantly less biodiversity and cannot support the larger predators needed to keep the mouse population under control.  Fewer predators lead to more mice and subsequently more ticks.

Why does it matter?

Ticks can carry and transmit a multitude of diseases to our pets and to us, including:

  • Lyme disease
  • Rocky Mountain spotted fever
  • Tularemia
  • Ehrlichiosis
  • Babesiosis
  • Anaplasma

For a more comprehensive list, check out the Center for Disease Control’s website:  httpss://www.cdc.gov/ticks/diseases/

What should we do?

While many tick-borne diseases are treatable and/or manageable if diagnosed, some diseases can be fatal for both pets and humans.  Therefore staying vigilant and protecting your pets and yourself is incredibly important.  Here are some tips:

  • Check frequently. We recommend daily tick checks to limit the time a tick is attached.  Check more frequently if you and/or your pet are traveling through grassy or wooded areas.  Transmission times vary greatly based on the pathogen (15 minutes to 24+ hours).
  • Note the following attachment site preferences:
    • Usually areas of thinner skin
    • American dog ticks prefer the scalp & head
    • Black-legged tick tends to attach on trunk or legs
    • Lonestar tick generally prefers areas below the waist. These ticks are most common in the southern U.S. but have been moving north.  They are present in Illinois and most recently spotted in Chicago as well.
  • Use tick preventives for your pet. Family Pet Animal Hospital carries various effective products for prevention and control including topical and oral products.  While we used to recommend preventives from April through November, due to changing weather patterns and the increase in cases of ticks we’ve seen even in the winter months, our veterinarians now recommend year round preventives for most pets.  Talk to your pet’s veterinarian to determine which preventive is right for your pet and his/her lifestyle.
  • Vaccinate against Lyme, when appropriate.  Discuss the Lyme vaccine with your pet’s veterinarian.  We do vaccinate against Lyme in some of our patients which are at a high risk of exposure.  However, because the Lyme vaccine’s efficacy is not 100% and it provides NO protection for other tick-borne illnesses, the veterinarians at Family Pet Animal Hospital consider preventive measures (vigilant tick checks and prompt removal along with effective oral or topical preventives) to be paramount for protecting your pet.
  • Test annually for common tick-borne illnesses.  As we began to see more cases of these illnesses, Family Pet Animal Hospital changed our canine standards of care for annual wellness checkups to include a 4DX test, which tests for not only heartworm, but also Lyme, Erhlichiosis, and Anaplasmosis.


According to Dr. Little, another thing to keep in mind is that ticks typically do not fall from trees.  Instead, ticks typically will crawl onto an animal from grass or ground litter.  From there, they will attach to and crawl up your clothes until they find a good feeding site.  Because ticks want to feed undetected for days or even weeks, they inject an anesthetic into their host that numbs the skin and delays the immune response (such as swelling or itching).  You or your pets are unlikely to feel a tick feeding, so make sure your checks are thorough!

See the additional resources below for more information on ticks, the diseases they carry, and their growing prevalence.

Additional resources:

Start your Dog’s or Cat’s Flea/Tick Preventive Now (includes 2016 Cook County Parasite Prevalence infographic).

Choosing the Right Heartworm, Flea, and Tick Prevention for your Dog

Companion animal Parasite Council – Ticks

Centers for Disease Control and Prevention – “Tickborne Diseases of the United States”

Beyond Lyme:  New Tick-Borne Diseases On the Rise in U.S.httpss://www.wbez.org/shows/all-things-considered/beyond-lyme-new-tickborne-diseases-on-the-rise-in-us/11ee9d0e-4c0d-450c-84b5-be8bd4f7ebc8


“Tick-Borne Illnesses Could Be On The Rise In Illinois This Summer.” WBEZ. N.p., 09 May 2017. Web. 09 May 2017.