Ticks Are on the Move: Disease Risks Rising Across the US

Tick-borne diseases are surging across the United States as changing climate patterns expand tick habitats into regions previously considered low-risk, health officials warn. Emergency room visits for tick bites have reached a nine-year high in 2026, with the Northeast recording 188 tick-related emergency visits per 100,000 people — the highest rate in the nation — followed closely by the Midwest.

An estimated 476,000 Americans are diagnosed and treated for Lyme disease each year, making it the most common tick-borne illness in the country. But Lyme is far from the only threat. As ticks expand their geographic range, they are bringing a growing roster of diseases — including anaplasmosis, babesiosis, Powassan virus, and Alpha-gal Syndrome — to communities that have never had to contend with them before.

A Rapidly Expanding Threat

The blacklegged tick, also known as the deer tick, is the primary vector for Lyme disease, anaplasmosis, and babesiosis. Historically concentrated in the Northeast and Upper Midwest, this species is now pushing into Ohio, Indiana, Illinois, and Michigan — states where Lyme disease was once considered rare.

Ohio illustrates the trend dramatically. The state reported just 40 cases of Lyme disease in 2010. By 2025, that number had surged to 2,830 — a nearly sevenfold increase in five years. As of May 2026, Ohio had confirmed 2,880 cases, with the highest concentrations in eastern counties.

Maine is experiencing a similar crisis. The state reported 4,257 cases of Lyme disease in 2025, up from 3,218 in 2024 — a 32 percent increase in a single year. State health officials now consider Lyme disease, anaplasmosis, babesiosis, hard tick relapsing fever, and Powassan virus endemic in Maine.

Multiple Species, Multiple Diseases

It is not just the blacklegged tick that is on the move. Several tick species are expanding their ranges across the United States, each carrying its own set of pathogens.

The lone star tick, traditionally found in the Southeast, is pushing into the Mid-Atlantic, Midwest, and Northeast. This species carries ehrlichiosis, tularemia, and Alpha-gal Syndrome — a potentially life-threatening allergy to red meat triggered by tick bites. The Gulf Coast tick has been detected as far north as Connecticut and Indiana, while the invasive longhorned tick, native to East Asia, has gained a foothold on the East Coast and begun moving westward.

According to Grist, researchers recently discovered that the Babesia parasite — which causes a malaria-like illness called babesiosis — is rapidly expanding through the mid-Atlantic. A study published in the Journal of Medical Entomology found the parasite in ticks collected in Virginia, Maryland, and Delaware, states where it had never before been detected in ticks. “Tick range expansion is occurring at such a precipitous rate that public health guidance regarding tick-borne disease prevention and treatment can be rapidly rendered obsolete,” the study authors warned.

Climate Change as a Driving Force

Climate change is the primary driver behind this expansion. Warmer winters boost tick survival rates, allowing more ticks to survive through cold months and emerge earlier in the spring. Milder temperatures also allow ticks to establish populations in areas that were previously too cold for them to survive.

Tick bite season is lengthening as a result. The CDC has reported that weekly emergency room visit rates for tick bites are the highest recorded for this point in the season since tracking began in 2017, across every region of the United States except the South Central states.

“Unfortunately, it seems that we are in for a very bad year,” Nicole Baumgarth, a professor of immunology and infectious disease at Johns Hopkins Bloomberg School of Public Health, told Newsweek. “We see an increasing number of tick infections, tickborne illnesses every year … and it’s unlikely this trend is going to change.”

Regional Risk Breakdown

Health officials have identified distinct risk profiles across different regions of the country:

Northeast: The highest-risk region, dominated by the blacklegged tick. Lyme disease, anaplasmosis, babesiosis, and Powassan virus are all present. Maine’s 32 percent year-over-year increase in Lyme cases underscores the growing threat.

Midwest: The second most affected region and the area of fastest growth. Lyme disease cases are rising rapidly in Ohio, Indiana, and Illinois. The lone star tick is also expanding into the region, bringing Alpha-gal Syndrome with it.

Mid-Atlantic: Babesiosis is emerging as a new threat in Delaware, Maryland, and Virginia. Alpha-gal Syndrome has been linked to urbanization patterns in the region.

Southeast: Historically higher risk for spotted fevers like Rocky Mountain spotted fever. The lone star tick is expanding northward out of the region.

West Coast and Mountain States: Lower overall risk compared to the eastern U.S., but the western blacklegged tick carries Lyme disease at lower rates, and higher elevations are seeing increased tick activity due to warming.

Emerging Threats Beyond Lyme

While Lyme disease remains the most prevalent tick-borne illness, newer threats are gaining attention. Powassan virus, which can be transmitted in as little as 15 minutes — compared to 24 to 36 hours for Lyme — is a growing concern in New England. Alpha-gal Syndrome, a red meat allergy triggered by lone star tick bites, is spreading into new areas. And babesiosis, a parasitic disease that mimics malaria, is expanding into the Mid-Atlantic.

Pennsylvania has begun tracking cases of Alpha-gal Syndrome after identifying approximately 600 cases over the past two years, according to Newsweek.

What This Means for Public Health

The rapid expansion of tick-borne diseases presents significant challenges for healthcare systems, particularly in regions with little prior experience diagnosing and treating these illnesses. The CDC’s reported cases significantly undercount the true burden — for Lyme disease, the estimated 476,000 annual cases are roughly five times the number actually reported.

Federal funding for tick-borne disease research also lags behind other infectious diseases. According to data from the Johns Hopkins Lyme and Tickborne Diseases Dashboard, federal funding per new reported case of Lyme disease stands at approximately $1,070 — a fraction of the funding per case for HIV/AIDS ($97,648) and hepatitis C ($47,522).

Looking Ahead

As climate change continues to reshape the American landscape, the geographic expansion of ticks and the diseases they carry is expected to accelerate. Public health officials emphasize that prevention — including tick checks, protective clothing, and prompt removal of attached ticks — remains the most effective defense.

For residents in newly affected areas, awareness is the first line of defense. The days when tick-borne diseases were a concern only for those in the Northeast or Upper Midwest are over. From Ohio to Maine, and from the Mid-Atlantic to the Mountain West, ticks are on the move — and the diseases they carry are following.