First Tick Infected with a Rare Tickborne Illness in Illinois Discovered in Lake County

CHICAGO – The Illinois Department of Public Health (IDPH) announced that the state’s active tick surveillance system has discovered the first tick in the state to test positive for Ehrlichia muris eauclairensis (EME), a bacteria transmitted by blacklegged tick bites that can cause human ehrlichiosis, a severe disease that can cause complications if not treated quickly. IDPH’s Vector Control Program is warning healthcare providers in Northern Illinois to be aware and on the lookout for ehrlichiosis, caused by EME. Ehrlichiosis can be easily treated with antibiotics, typically doxycycline, but can cause severe illness if left untreated.

The blacklegged tick, also called a deer tick, was collected on May 17 by Lake County Health Department staff who receive funding through IDPH’s Environmental Health Tick Surveillance Grant program. The tick was recently tested and confirmed positive for EME by the CDC. Along with ehrlichiosis, ticks submitted by IDPH to CDC are tested for several diseases of human-health importance, including Lyme disease, babesiosis, anaplasmosis, and Borrelia miyamotoi disease.

The disease was first discovered in an Eau Claire County, Wisconsin, resident in 2009. All known human cases of EME have occurred in Wisconsin and Minnesota. In Illinois, ehrlichiosis is primarily seen in Southern Illinois and spread through the bites of infected Lone star ticks. With the Lake County discovery, a second tick species is now known to spread ehrlichiosis in Illinois. Infected adult and young blacklegged ticks can spread EME to people. Blacklegged ticks are commonly found in areas with woods, brush, leaf litter, and tall grass. Adult blacklegged ticks are active from October-December and any winter day above freezing.

“The discovery of the first tick in Illinois carrying EME, a rare and serious disease, is a great reminder of the importance of our active tick surveillance program in Illinois,” said IDPH Director Dr. Sameer Vohra. “Tickborne illnesses such as Lyme disease and EME can cause severe illness, especially if untreated. Anyone who spends time in wooded areas or brush, including hunters, should be sure to check for ticks every few hours and remove any that you find. If you experience common symptoms of tickborne illnesses - such as fever, sweats, chills, muscle aches, nausea or vomiting – see your healthcare provider immediately and let them know about tick exposure so that you can obtain testing and treatment that can prevent serious illness.”

The announcement of the discovery of a new pathogen in Illinois comes ahead of the 2024 Illinois Tickborne Disease Conference on October 22 in Champaign. The conference is hosted by IDPH, the Southern Illinois University School of Medicine and the Illinois Lyme Association. It brings together clinicians, health care providers, researchers, local health departments, and other leaders in the field of Lyme and tickborne diseases. The conference provides an opportunity to educate clinicians, researchers, local health departments, and community advocates on Lyme and other tickborne diseases and state-of-the-art, evidence-based treatment and prevention strategies. 

Following are additional tips for how to avoid tickborne illnesses and have a healthy time outdoors:

• Learn about tick removal and symptom awareness HERE.
• Walk in the center of trails. Avoid wooded, bushy areas with high grass and leaf litter.
• Wear light-colored clothing to make ticks easier to find. Tuck long pants into socks and boots.
• Apply an EPA-registered insect repellent containing 20% DEET, picaridin, IR3535, or Oil of Lemon Eucalyptus according to label directions. The EPA has a search tool that can help you find the product that best suits your needs.
• Treat outdoor clothing and gear with 0.5% permethrin.
• Conduct full-body tick checks on family members (underarms, ears, belly button, behind knees, between legs, waist, hair and scalp) every two to three hours. Also check any gear or pets taken on outings.
• Put your clothes in the dryer on high heat for 10 minutes (or one hour for damp clothes) to kill ticks.
• Shower within two hours after coming indoors.
• If you find a blacklegged tick on you that may have been attached for more than two days, then seek medical attention to decide if you need an antibiotic to prevent Lyme disease.
• It is often helpful to keep the tick for species identification. Place the tick in rubbing alcohol or in a sealed bag/container to bring to your healthcare provider or local health department for submission to IDPH.  A submission form can be found HERE  on the IDPH website.

For more information, check out IDPH’s interactive Tick Surveillance Map that documents the counties in Illinois where the different tick species have been confirmed as well as the diseases they may carry. If you are a clinician, click HERE for more information about Lyme Disease and click HERE for more information about Rocky Mountain Spotted Fever