Lyme disease was once thought of as a problem concentrated in the Northeast and a few Midwest states. That geographic assumption is no longer accurate. Deer ticks — the primary carrier of the Lyme disease bacterium — are now establishing themselves in Ohio, Indiana, Illinois, and Michigan, areas where they were rarely found just a generation ago.
Emergency department visits for tick bites were up more than 25 percent in April 2026 compared to April 2025, according to CDC data cited at a Johns Hopkins Bloomberg School of Public Health media briefing on May 5, 2026. Researchers called it an early signal of what could be a challenging year ahead.
Why This Matters
Lyme disease is the most common vector-borne illness in the United States, and it is underreported by a wide margin. State health departments reported more than 89,000 confirmed cases to the CDC in 2023 — the most recent year for which national data were published, but researchers estimate the true number is closer to half a million annually, largely because of misdiagnosis and underreporting in areas where the disease is newly arriving.
For residents of expanding-risk states, this matters in a very practical way: your doctor, your local emergency room, and even the diagnostic tests used to confirm Lyme disease may not be calibrated to a disease that was once considered rare in your area. Early Lyme disease is treatable with antibiotics, but a delayed diagnosis can lead to more serious complications, including neurological and cardiac involvement.
What We Know So Far
The Companion Animal Parasite Council’s 2026 annual forecast — which tracks tick populations and disease risk — identifies Ohio, Kentucky, West Virginia, Tennessee, North Carolina, Indiana, Illinois, and Michigan as projected areas of significant Lyme disease expansion. The forecasts have historically been 94 percent accurate when compared to actual diagnostic results.
The Upper Midwest and Northeast remain the highest-risk regions overall, with Minnesota, Wisconsin, Pennsylvania, New York, New Jersey, and Connecticut continuing to account for the largest share of confirmed cases. But the expansion is moving steadily south and west.
According to Contagion Live, Dr. Elitza Theel, a Mayo Clinic infectious disease microbiologist, noted that “these cases have progressively spread into more Midwest states, such as Ohio, Pennsylvania, Indiana, and Illinois,” and attributed the spread to both tick range expansion and the proliferation of environmental reservoirs — particularly white-footed mice and deer.
Where the Risk Is Highest
Pennsylvania remains among the highest-burden states in the nation for both Lyme disease and related tick-borne conditions. The state is also now formally tracking cases of alpha-gal syndrome — a rare red meat allergy triggered by tick bites from the lone star tick — adding another dimension to tick-related health risk.
Within the broader risk map, the CAPC forecast projects that some of the greatest expansions in Lyme disease risk in 2026 will occur in Ohio, Kentucky, West Virginia, and parts of Tennessee and North Carolina — states that until recently saw very few cases. Iowa is also identified as a higher-than-normal risk area, particularly in the southeastern part of the state, due to forested river corridors along the Mississippi and Iowa rivers.
In Indiana, blacklegged ticks have now been found in almost every county, according to Purdue University’s Medical Entomology program. The tick was first discovered in the state of northwestern Indiana in 1987 and has since expanded rapidly.
What Doctors and Experts Say
Dr. Thomas Hart, an infectious disease microbiologist at the Johns Hopkins Bloomberg School of Public Health’s Lyme and Tick-Borne Diseases Research and Education Institute, explained the environmental drivers at the May 2026 briefing: “This increase in tick populations is going to be caused primarily by climate change. Warmer, milder winters are great for ticks to survive to the next year without freezing. And it also helps the animals that the ticks feed on — deer and mice — survive at greater populations.”
Dr. Nicole Baumgarth, a Bloomberg Distinguished Professor at Johns Hopkins, noted that suburban expansion into wooded areas is another key contributor: human activity is increasingly bringing people into contact with tick habitat that was previously less accessible.
What the Evidence Shows — and What It Does Not
Researchers at Johns Hopkins have noted a well-documented challenge that comes with geographic expansion: diagnostic gaps. Lyme disease is confirmed using a blood test that detects antibodies, but antibodies may take several weeks to develop after infection. A test done too early can come back negative even in an infected patient.
This limitation matters more in newly expanding regions, where physicians are less accustomed to suspecting Lyme as a diagnosis, and patients are less likely to report a tick bite as a relevant medical history item.
Established science shows that early Lyme disease, caught within days to a few weeks of a tick bite, responds well to oral antibiotics. Later-stage disease — which can involve the joints, heart, and nervous system — requires more intensive treatment and may have lingering symptoms even after treatment is complete.
Who Faces the Greatest Risk?
People most at risk for Lyme disease in 2026 include:
- Outdoor workers in landscaping, forestry, agriculture, and construction in the Northeast and expanding Midwest
- Hikers, campers, hunters, and people who spend time in wooded or grassy areas
- Children between 5 and 15 years old, who show consistently higher case rates in national surveillance
- Adults between 45 and 55, the other age group with elevated case rates
- Residents of newly endemic counties in Ohio, Indiana, Illinois, and Michigan who may not recognize tick exposure as a health concern
- Pet owners whose dogs spend time outdoors and can carry ticks into the home
Symptoms and Warning Signs to Watch For
Early Lyme disease — within the first three to 30 days after a tick bite — may cause:
- A bull’s-eye rash (erythema migrans) at the bite site, though this rash does not appear in all cases
- Fever, chills, and fatigue
- Muscle and joint aches
- Headache
- Swollen lymph nodes
Later symptoms, if the infection goes untreated, may include severe joint pain and swelling, neurological problems such as facial palsy or numbness, heart rhythm irregularities, and cognitive difficulties.
Contact a health care provider promptly if you find an attached tick, develop a rash near a bite site, or experience fever and fatigue following outdoor activity in a tick-prone area.
What You Can Do Now
- Use EPA-registered insect repellents with DEET (20–30 percent), picaridin, or IR3535 on exposed skin when outdoors in wooded or grassy areas.
- Wear long sleeves and pants, and tuck pants into socks when hiking in tick habitat.
- Perform a full-body tick check — including scalp, behind the ears, under the arms, and between the legs — after any outdoor activity.
- Remove attached ticks promptly using fine-tipped tweezers, pulling upward with steady pressure. Do not twist or crush the tick.
- Shower within two hours of coming indoors after outdoor activity.
- Talk to your veterinarian about tick prevention for dogs, which can also bring ticks into your home.
- If you find an attached tick or develop symptoms after potential exposure, contact a clinician. Do not wait for the rash — not everyone with Lyme disease develops the classic bull’s-eye pattern.
Cost and Access: What Patients Should Know
Standard Lyme disease testing is typically covered by health insurance, though the two-step testing protocol may require a laboratory order and follow-up confirmatory testing. Patients in newly expanding areas who suspect tick exposure should be specific with their health care provider about their outdoor activities and location.
In areas with limited primary care access, telehealth can be a practical option for initial evaluation and a discussion of whether testing and empiric treatment are warranted. Oral antibiotics such as doxycycline, amoxicillin, and cefuroxime are effective for early Lyme disease and are widely available and relatively low-cost in generic form.
What Happens Next
The 2026 tick season is expected to remain active through October in most of the affected region. Researchers at Johns Hopkins are continuing work on Lyme disease diagnostics and are monitoring a pipeline of Lyme vaccines, though none is currently approved for human use in the United States. Updated CDC case data for 2024 are expected to be published later in 2026 and may confirm the geographic expansion already visible in tick surveillance data.
The Bottom Line
Lyme disease is no longer confined to the Northeast. If you live in Ohio, Indiana, Illinois, Michigan, or other expanding-risk areas, the risk of tick exposure in 2026 is meaningfully higher than it was just a few years ago. The best protection is simple and well-established: repellent, protective clothing, prompt tick checks, and early medical attention if you develop symptoms after possible tick exposure. Do not wait for the classic bull’s-eye rash, which is absent in a meaningful share of cases.