Understanding and preventing tick-borne disease in Pennsylvania 

Pennsylvania is one of the top states in the U.S. for reported cases of Lyme disease and other tick-borne illnesses. To better understand the risks and how to stay safe, we spoke with Erika Machtinger, a Penn State researcher who studies tick ecology, disease transmission, and prevention strategies.

Is Pennsylvania a high-risk state for ticks and Lyme disease?

Yes—Pennsylvania consistently reports the highest number of total Lyme disease cases in the country, with about 30% of all recorded cases nationally. While we don’t top the list in terms of incidence per capita, we’re still ranked high even after adjusting for population.

All 67 counties in the state have both the blacklegged tick (the primary vector for Lyme disease) and documented cases of Lyme. We also have other tick species that carry different risks. What’s particularly concerning is that cases of tick-borne disease continue to rise, and tick populations are expanding geographically within the state.

How is the threat from ticks and Lyme disease evolving in Pennsylvania?

We're seeing multiple changes:

• Increased case counts for Lyme disease and other tick-borne infections.
• Expanding geographic ranges of native ticks, as well as new species moving in, like the lone star tick (which can trigger red meat allergies) and the invasive longhorn tick (a concern for livestock and wildlife).
• Shifts in seasonal activity, likely due to climate change, are causing ticks to become active earlier in the year.
• Changes in the tick life cycle that could impact the transmission of diseases.

A lot of this is due to human-driven changes—land development, the movement of people and animals, and ecological shifts over the last century. For example, predators of deer and small mammals (like wolves and mountain lions) were extirpated from the region, which helped increase populations of animals that are good hosts for ticks and can carry the pathogens that we are concerned about.
 

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How are climate change and land-use changes affecting tick-borne disease in Pennsylvania?

The short answer is they’re making things more complicated. Climate change, urbanization, and landscape fragmentation are expanding tick habitats and enabling new tick species—and the diseases they carry—to move into areas where they weren’t previously found.

For example, ticks are now established in places like coastal Maine, which used to be largely free of them. We’re also seeing previously southern species, like the lone star tick, move northward. These changes mean that Pennsylvanians may be at risk in places they weren’t before, like city parks or suburban gardens.

Public awareness is key. The goal isn’t to scare people, but to help them recognize the risk and take protective steps.

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What are the most common myths about ticks and Lyme disease?

There are quite a few! Here are the most common ones we encounter:
 

Myth: You should remove a tick with Vaseline, nail polish, or a hot match.
The safest way is to use tweezers to grasp the tick close to the skin and pull straight out. These other methods can irritate the tick and cause it to regurgitate pathogens into your body.

Myth: You must remove the tick's "head."
Ticks don’t have heads like insects. The part that stays embedded is the mouthpart. If a small piece remains, your body will usually expel it naturally.

Myth: Deer carry the pathogen that causes Lyme disease.
Deer are important for feeding adult ticks, but don’t carry the Lyme disease pathogen. Small rodents, like mice and chipmunks, and some ground-dwelling bird species, like robins, are the key reservoirs that we know about.

Myth: Ticks are only found in the woods.
Ticks can be found in urban parks, backyards, gardens—anywhere hosts like mice, birds, or deer can travel.

Myth: All ticks carry Lyme disease.
Only the blacklegged (deer) tick transmits the Lyme disease pathogen in the Northeastern United States. However, other ticks can have other pathogens or can cause other conditions we are concerned about, like the lone star tick and alpha-gal syndrome.
 

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How can I prevent tick bites and find ticks early, especially during peak seasons?

Prevention is the most practical and effective approach. Here are the most important steps:

1. Use EPA-registered repellents like DEET, picaridin, IR3535, or oil of lemon eucalyptus. These have been tested for both effectiveness and safety.
    
2. Wear permethrin-treated clothing or treat your own clothes using products sold in outdoor stores. This is one of the most effective ways to keep ticks from biting.
    
3. Dress smart: Light-colored clothing helps you spot ticks more easily. Tuck pants into socks and shirts into pants to keep ticks from reaching your skin.
    
4. Do tick checks: After being outdoors, inspect your body, take a shower, and check your pets. Ticks often attach in hidden areas like behind the knees, armpits, or at the hairline.
    
5. Protect your pets: Talk to your veterinarian about flea and tick preventatives that are appropriate for your animals.

At Penn State Extension, we offer helpful resources, including videos that demonstrate how to apply permethrin and perform tick checks. https://extension.psu.edu/insects-pests-and-diseases/vectors
 

What are the most effective ways to control ticks in yards and communities?

Tick systems are complex, and unfortunately, there’s no one-size-fits-all solution. Ticks depend on both environmental conditions and animal hosts, which makes them harder to control than flying insects like mosquitoes. That said, some effective integrated pest management (IPM) strategies include:

• Habitat management: Keeping yards clear of leaf litter, trimming overhanging vegetation, and removing invasive shrubs like Japanese barberry can make environments less tick-friendly.
   
• Targeted pesticide applications: Acaricides (tick-killing pesticides) can be applied in spring and fall. These are effective, but some people prefer to avoid synthetic chemicals.
   
• Rodent-targeted methods: Our team and others are testing an oral vaccine designed for rodents that could prevent them from carrying the pathogen responsible for Lyme disease. While the ticks themselves aren’t killed, this approach aims to break the cycle of disease transmission by stopping ticks from acquiring the pathogens in the first place.
   
• Tick tube research: We’re also studying how tick tubes can use rodents’ natural nesting behavior to deliver a tick-killing treatment, called permethrin, directly to mice. By treating the animals that ticks frequently feed on, this method targets ticks where they’re most vulnerable. We're collaborating with other universities in a multi-site study to evaluate and optimize its effectiveness across different environments.
   
• Anti-tick and Lyme vaccines: Several research groups are developing anti-tick vaccines designed to trigger an immune response in people, pets, or livestock that helps the body recognize and repel ticks before they can feed and transmit disease. Additionally, a human Lyme disease vaccine is currently in clinical trials in Pennsylvania and may become available soon.

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Tick-borne diseases are a growing concern, but knowledge is power. With a few simple precautions and greater awareness, Pennsylvanians can enjoy the outdoors while minimizing their risk.

Erika Machtinger is an associate professor of entomology at Penn State who uses her research to inform and improve public health education and promote awareness of the risks posed by pests such as ticks. Her research is multidisciplinary and integrated, with a focus on pests of veterinary concern. One of her primary research interests is tick ecology and tick-host interactions. She works to understand the behaviors and interactions between ticks and their animal hosts. She is also the Vector-borne Disease Team leader at Penn State Extension, where she delivers science-based education to the public on human and animal vector-borne disease education priorities.