‘These are worrisome numbers,’ OHIO researchers work to prevent Lyme disease in Ohio and Appalachia

‘These are worrisome numbers,’ OHIO researchers work to prevent Lyme disease in Ohio and Appalachia

Lyme disease is the most common tickborne illness in Ohio, and the number of cases have significantly increased in recent years. Mario J. Grijalva, Ph.D., director of ��’s Infectious and Tropical Disease Institute, explains the cause of this increase and the University's role in Lyme education and prevention.

Alex Semancik | July 24, 2025

Ticks are tiny, but the diseases they carry can cause large, life-altering health problems.

Adult ticks are only about the size of an apple seed, and nymphs can be as small as a poppy seed, but both bite humans and animals to feed, potentially infecting them with Lyme disease.

Lyme disease is the most common tickborne illness in Ohio, and the number of Lyme disease cases in the state have significantly increased during each of the past three years. In 2022, 554 cases were reported, that number grew to 1,301 in 2023 and 1,788 in 2024, according to data from the . As of June 2025, there are already 660 cases reported.

This image depicts a lone star tick, Amblyomma americanum, nymph, that was crawling on a person’s fingernail. — This image depicts just how small a lone star tick nymph is. (Photo courtesy CDC's Public Health Image Library)

Mario J. Grijalva, Ph.D., director of ��’s Infectious and Tropical Disease Institute says these are worrisome numbers. Grijalva is a professor of microbiology in OHIO’s Heritage College of Osteopathic Medicine and an internationally recognized expert on the spread of infectious disease.

“[Reported Lyme disease cases] likely represent the tip of the iceberg,” said Grijalva. “Many people infected with Lyme disease go undiagnosed or are treated rapidly by their physicians based solely in their clinical presentation. Unconfirmed cases may not be reported or submitted for confirmation. Therefore, those cases do not make it into the statistics.”

Dr. Mario Grijalva is an internationally recognized expert on the spread of infectious disease. As he did in Ecuador, Grijalva hopes to build a collaborative network of experts to develop research and education initiatives that address infectious diseases, such as tick-borne diseases, that negatively impact the health of those living in Appalachia.

Grijalva says there are likely several reasons for the increase in Lyme disease case numbers in Ohio. The population of blacklegged (deer) ticks—the species that carries Lyme disease—has continued to increase and the areas the inhabit have expanded. In addition, there is a reported increase in outdoor recreational activities after the COVID-19 pandemic, which brings more people into tick-infested areas.

“Warmer winters, changes in land use and increases in white-tailed deer and small mammal populations (key hosts for ticks) all create ideal conditions for Lyme disease’s causative agent the bacterium Borrelia burgdorferi, to be readily transmitted to people,” explained Grijalva. “Since it is unlikely that the trend of an increasing tick population will change or that there will be less human-tick contact in upcoming years, we should expect cases to continue rising.”

OHIO’s role in education and prevention

��’s Infectious and Tropical Disease Institute is actively developing research projects and outreach programs in southeast Ohio communities to raise awareness, promote prevention and understand what the increase in ticks and Lyme disease cases means for the region.

The Appalachian Ohio Tick Project is a collaborative effort to increase public awareness about tickborne diseases, improve surveillance and share prevention strategies with residents, schools, and outdoor workers. �� Zanesville recently focused on the growing threat of Lyme disease.

The workshop, aimed at engaging high school students and their teachers in vital research into tick-borne illnesses, provided a deep dive into the ecology of ticks and the diseases they carry, particularly Lyme disease. Participants received training in both theoretical knowledge and practical skills, crucial for their roles as educators in their communities.

Participants at the Zanesville Appalachian Ohio Tick Project Workshop learn about black-legged ticks.

Participants of the Appalachian Ohio Tick Project workshop were immersed in a series of engaging activities, from fieldwork estimating tick densities to laboratory exercises such as DNA extraction and gel electrophoresis.

The workshop, held at the �� Zanesville campus, allowed participating teachers to gain experience with the field and laboratory methods that their students will use in their courses.

“Our Institute recognizes the importance of Lyme disease in the larger Appalachian region,” said Grijalva. “Active collaboration with public health departments in all Appalachian counties within Ohio is key in these endeavors, since strengthening their capacity is the best way to fight Lyme disease.”

The Infectious Diseases in Appalachian Ohio initiative seeks to showcase the strengths of local health departments and organizations while identifying critical needs for long-term success. �� offers valuable resources to support and collaborate with Appalachian communities in addressing these challenges.

Mario Grijalva speaks at the first Infectious Diseases in Appalachian Ohio Summit.

At the inaugural Infectious Diseases in Appalachian Ohio Summit experts discussed the dramatic rise in tickborne diseases, as well as potential solutions. Speakers and attendees spoke about how the region needs to better address infectious disease, how the University could assist local health leaders to prevent, communicate about and take action to fight infectious diseases, how data collection and sharing could be improved, current best practices and gaps in testing protocols and whether health care providers are effectively diagnosing and reporting infectious diseases. Improving testing is one potential solution.

“Early detection is key to preventing severe disease. While laboratory testing has limitations early in infection, awareness of clinical signs and risk factors is crucial,” explained Grijalva. “We are working with the Athens City-County Health Department who is setting up tick testing laboratory. This is a new service that would improve control, prevention and case detection in Southeast Ohio.”

Prevention and treatment

In Ohio, cases of Lyme disease are every month of the year, but people are most at risk when ticks are most active in late spring through mid-summer. June and July are the months most Ohioans are bitten by Lyme-infected blacklegged ticks.

As Grijalva said, early detection is key. If you notice you have been bitten by a tick Grijalva suggests:

Remove it promptly using fine-tipped tweezers.
Grasp the tick close to the skin and pull steadily upward.
Clean the bite area with soap and water.
Save the tick in a sealed container or bag (labeled with the date) in case identification is needed.
Monitor for symptoms for several weeks.