Ticks are well-established parasites in Illinois, and their presence is a growing public health concern as tick-borne disease cases increase across the state. These arachnids feed on the blood of animals and humans and can transmit a range of illnesses during the feeding process. Understanding the specific types of ticks found in the region and the risks they pose is the foundation for effective personal protection, especially for anyone spending time outdoors.
Common Tick Species Found in Illinois
The Illinois environment supports multiple tick species that occasionally bite humans, with three species being the most frequently encountered. The American Dog Tick, often called the Wood Tick, is the most common. It is reddish-brown, measuring about 3/16 of an inch long before feeding. Female American Dog Ticks are distinguishable by a large, silver-colored spot located just behind the head.
The Blacklegged Tick, widely known as the Deer Tick, is smaller, typically measuring about 1/8 of an inch. It is reddish-brown with dark, almost black, legs. The females of this species have a distinct red-orange body that contrasts with their dark legs and dorsal shield. Its diminutive size, especially the pinhead-sized nymph stage, often allows it to go unnoticed.
The Lone Star Tick is a small, brown tick found predominantly in the southern half of the state. The adult female is easily identified by a single, prominent, whitish or silvery spot located in the middle of her back.
Seasonal Activity and Preferred Habitats
Ticks in Illinois show activity throughout the year, though the risk of exposure is highest during the warmer months, generally from April through September. Different species exhibit peak activity at various times. For example, the American Dog Tick adults are most active during the spring and early summer, typically peaking in April, May, and June. The Lone Star Tick also shows heightened activity during the spring and summer, from April through the end of July.
Ticks do not fly or jump; instead, they wait on vegetation for a host to brush by, a behavior called questing. Their preferred environments offer moisture and cover, such as wooded areas, the edges of trails, and areas with thick underbrush and leaf litter. They are also frequently found in tall grasses and meadows. Even urban and suburban areas, including local parks and overgrown backyards, can harbor tick populations.
Major Tick-Borne Illnesses in Illinois
The most widely recognized tick-borne illness in Illinois is Lyme disease, a bacterial infection transmitted primarily by the Blacklegged Tick. A telltale sign of early infection is the Erythema Migrans rash, a circular red lesion that appears in 70 to 80 percent of cases within three to 32 days of the bite. The rash often expands gradually and may clear in the center, creating the characteristic “bull’s-eye” appearance, though it is usually not painful. Early symptoms also include non-specific flu-like complaints, such as fever, chills, fatigue, headache, and muscle or joint pain.
Rocky Mountain Spotted Fever (RMSF) is a serious bacterial disease, primarily carried by the American Dog Tick and occasionally by the Lone Star Tick. Symptoms typically manifest between three and 14 days after the infected bite, beginning with a sudden onset of high fever, severe headache, and deep muscle pain. A rash, which can start as small red spots on the wrists, ankles, palms, or soles, appears in most cases but is not always present, which can delay diagnosis. Early diagnosis is important, as treatment with appropriate antibiotics must begin within the first five days of symptoms to prevent severe complications, including brain swelling and potential fatality.
Ehrlichiosis is a bacterial illness transmitted by the Lone Star Tick and, to a lesser extent, the American Dog Tick and Blacklegged Tick. Symptoms usually develop five to 14 days following the bite and are often non-specific, resembling a mild flu. These symptoms include fever, chills, headache, muscle aches, and fatigue. Gastrointestinal issues like nausea and vomiting may also occur, and a rash is more common in children than in adults. If left untreated, Ehrlichiosis can lead to life-threatening complications, including respiratory distress and renal failure, underscoring the need for timely medical intervention.
Prevention Measures and Safe Removal Techniques
Reducing the risk of tick bites involves taking practical steps when spending time in wooded or grassy areas. Wearing long-sleeved shirts and long pants tucked into socks creates a physical barrier against ticks climbing onto the skin. Light-colored clothing is also helpful, as it makes it easier to spot ticks crawling on the fabric before they can attach.
Applying a repellent containing at least 20 percent DEET to exposed skin will deter ticks. Treating clothing and gear with a product containing 0.5 percent permethrin can kill ticks on contact. After returning indoors, performing a thorough tick check on yourself, children, and pets is necessary for finding and removing any attached ticks. Ticks can also be removed from clothing by placing the garments in a dryer on high heat for at least ten minutes.
If a tick is found attached to the skin, safe and prompt removal is the best defense against disease transmission. Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible, ideally near the mouthparts. Pull upward with steady, even pressure without twisting or jerking, which could cause the mouthparts to break off in the skin. After removal, the bite area and your hands should be thoroughly cleaned with rubbing alcohol, an iodine scrub, or soap and water.