Ticks in Illinois: The rising risk of Ehrlichiosis

Ehrlichiosis is a budding concern for those who love the Illinois outdoors, especially as awareness grows around tick-borne diseases in general. As people take to the woods, hike trails, or participate in other outdoor activities, the risks of encountering disease-carrying ticks increase.

Ehrlichiosis is one such disease, and although it may not get as much attention as other tick-borne diseases, it can pose some serious health risks.

What is Ehrlichiosis?

Ehrlichiosis is a bacterial illness caused by certain strains of the Ehrlichia bacteria, and it’s transmitted to humans through tick bites. The disease can impact the body’s white blood cells, leading to a range of symptoms that can be mild to severe, according to the Illinois Department of Public Health (IDPH). The bacteria also affects the immune system and sometimes causes life-threatening complications.

Ehrlichiosis isn’t as well-known as Lyme disease or Rocky Mountain spotted fever, but its prevalence is growing in parts of the United States—including Illinois.

Ticks Responsible for Ehrlichiosis

In Illinois, Ehrlichiosis is most commonly spread by the Lone Star tick. This tick species is found in many parts of the Midwest and is particularly abundant in southern and central Illinois, residing in wooded areas and tall grasses. The Lone Star tick has become increasingly recognized as a carrier of Ehrlichia bacteria.

But on October 18, 2024, IDPH announced the discovery of a new tick pathogen called Ehrlichia muris eauclairensis (EME), which also can cause Ehrlichiosis in humans. This time, however, the EME pathogen was found in a blacklegged tick by the Lake County Health Department. With the onset of this news, public health officials have learned that two tick species are now capable of transmitting Ehrlichiosis in the state.

As of October 16, 2024, an Illinois Tick Surveillance Map from IDPH indicates that various species of Ehrlichia have been found in more than 25 counties in the state and counting.

The increasing prevalence of the tick-borne disease is attributed to factors like warmer temperatures year-round and habitat modifications, which has allowed the ticks to gain traction in more regions than before.

Symptoms of Ehrlichiosis

Ehrlichiosis symptoms generally develop between 5 and 14 days after being bitten by an infected tick. Unlike bug or insect bites, tick bites don’t cause pain, so many people don’t know that they’ve even been bitten.

Some early signs of Ehrlichiosis infection include:

• fever
• chills
• headaches
• muscle aches
• fatigue

An infected person may also experience a range of gastrointestinal symptoms, such as nausea, vomiting, diarrhea, and loss of appetite. Certain people, especially children, can develop a rash, although it tends to be a less common symptom.

Because Ehrlichiosis symptoms tend to be general, many people may not realize they have the tick-borne disease until it progresses. Early diagnosis is crucial, but there’s no way to tell if you’ve contracted the illness for sure unless you have laboratory testing, so it can sometimes be challenging to diagnose.

What Can You Do About It?

The best way to reduce your risk of Ehrlichiosis and other tick-borne diseases is to take preventative measures. When you head outdoors, you can reduce your chances of coming in contact with ticks using the following tips:

1. Wear protective clothing: Long sleeves, long pants and boots help limit skin exposure. Tucking pants into socks creates an additional barrier.
2. Use tick repellents: Apply insect repellent containing at least 20 percent DEET on exposed skin. Treating clothing with permethrin can provide an extra layer of protection.
3. Perform tick checks: After you’ve been outdoors, check yourself, your family, and your pets for ticks. Pay attention to hidden areas like under the arms, round the waist, and behind the knees, and use a mirror to help you check hard-to-see areas.
4. Remove ticks promptly: If you find an attached tick, carefully remove it using a pair of fine-pointed tweezers. Don’t twist, jerk, or burn it.
5. Take note of symptoms: If you develop symptoms such as fever or muscle aches after being outdoors or having a tick bite, it’s a good idea to consult with a healthcare professional. Ehrlichiosis can be effectively treated with certain antibiotic medications if caught early.

Although it’s important to remain tick-aware, ticks don’t have to keep you from heading outdoors. By taking preventive measures and watching for early signs and symptoms, residents and visitors alike can enjoy the state’s natural beauty while minimizing the chances of coming in contact with ticks any time of the year.

Resources
Ehrlichiosis. Illinois Department of Public Health website.

Illinois Tick Surveillance Map. Illinois Department of Public Health website.

Lone Star Tick Surveillance. Centers for Disease Control and Prevention website.

Signs and Symptoms of Ehrlichiosis. Centers for Disease Control and Prevention website.

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Jenny Lelwica Buttaccio, OTR/L, is a health journalist based in Indiana and licensed occupational therapist. She lives with her husband and rescue dogs Emmi and Opal. When not writing, she can be found buried in a book, working out, or out in nature. Her work has been featured in HuffPo, Prevention, Men’s Health, Healthline and many other publications.