WHERE IS LYME DISEASE IN OHIO
Lyme Science Blog
Apr 20

Where Is Lyme Disease in Ohio? Counties at Highest Risk

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Can You Get Lyme Disease in Ohio? Cases Are Rising

Lyme disease cases in Ohio are rising sharply. Once considered a low-risk state, Ohio is now seeing a significant increase in reported infections—challenging long-standing assumptions about where Lyme disease occurs.

Recent data show thousands of cases annually, with a dramatic increase over the past decade. This shift suggests Lyme disease is no longer emerging in Ohio—it is already established.

Recent data from the Ohio Department of Health show 137 reported cases as of early 2026, with marked variation by county—reinforcing that Lyme disease risk is not evenly distributed across the state.

“If Lyme disease wasn’t supposed to be common in Ohio, why are cases increasing so quickly?”

Ohio Lyme Disease Trend:
• ~40 cases (2010)
• ~415 cases (2020)
• 2,800+ cases recently

Earlier research had already suggested this trend was underway. A study from Ohio State University and the Ohio Department of Health documented the spread of black-legged ticks (Ixodes scapularis)—the primary vector of Lyme disease—across the state, laying the groundwork for what we are now seeing clinically.


Lyme disease Ohio tick map

Deer tick distribution in Ohio (Glenn Needham)


Lyme Disease Is Now Established in Ohio

The study, published in Frontiers in Cellular and Infection Microbiology, found deer ticks in 57 of Ohio’s 88 counties as of 2012.

Researchers confirmed the full enzootic life cycle of Borrelia burgdorferi, the bacterium responsible for Lyme disease.

This means Lyme disease is no longer emerging in Ohio—it is established.

The presence of larvae, nymphs, and adult ticks indicates sustained transmission within the environment.


Why Ticks Are Spreading

The expansion of deer ticks in Ohio has been attributed to several factors:

  • Migratory birds transporting infected ticks
  • Deer movement across regions
  • Human environmental changes

These factors allow Lyme disease to spread into areas previously considered low risk.


The Surveillance Problem

Despite growing evidence, the CDC has historically classified Ohio as a non-endemic state.

This classification may underestimate actual risk.

Ohio’s own tick surveillance program—operating since 1983—provided valuable data but lost funding and was discontinued in 2012.

Without consistent surveillance, emerging risk may go unrecognized.


Why This Matters Clinically

Physicians often rely on CDC surveillance maps when assessing Lyme disease risk.

If a region is considered low risk, Lyme disease may not be included in the differential diagnosis.

This can lead to:

  • Delayed diagnosis
  • Missed treatment opportunities
  • Progression to chronic illness

The consequences of under-recognition can be significant.


The “Non-Endemic” Myth

At our practice, we have treated patients from across the United States—including those infected in states traditionally labeled as non-endemic.

Lyme disease does not respect geographic boundaries.

As tick populations expand, the concept of “non-endemic” regions becomes less reliable.

Wondering where Lyme disease risk is highest within Ohio?
See which areas in Ohio are most affected.


Clinical Perspective

Clinicians should consider Lyme disease in patients with compatible symptoms—even in areas not officially recognized as endemic.

Geographic assumptions should not replace clinical judgment.

Early recognition and treatment remain critical to preventing long-term complications.

For more information on ticks and the diseases they transmit, visit:
About ticks and tick-borne diseases


References

  1. Wang P, Glowacki MN, Hoet AE et al. Emergence of Ixodes scapularis and Borrelia burgdorferi in Ohio. Front Cell Infect Microbiol, 2014.
  2. Ohio Department of Health. Lyme Disease in Ohio: County-Level Data and Trends, 2026.

    https://odh.ohio.gov/know-our-programs/zoonotic-disease-program/media/lyme-disease-map

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

SymptomsTestingCoinfectionsRecoveryPediatricPrevention

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