Lyme Disease is a common and serious tick-borne illness that can be difficult to diagnose, and both early recognition of infection and prompt treatment are important. Unfortunately, a new study says many hikers on the Appalachian Trail are unable to recognize one of the key indicators that an individual may have contracted the illness.

The study, conducted by four health-care professionals, is being published in the journal Wilderness and Environmental Medicine, and the authors note, "Lyme disease is the most common vector-borne infectious disease in North America. With nearly 2,500 Appalachian Trail (AT) hikers entering the endemic area for as long as 6 months, exposure to the disease is likely."

The Appalachian Trail runs for nearly 2,200 miles from Maine to Georgia, and is "managed by the National Park Service, U.S. Forest Service, Appalachian Trail Conservancy, numerous state agencies and thousands of volunteers." Along the way, the route pass through several NPS areas, including Delaware Water Gap National Recreation Area, Shenandoah National Park, and Great Smoky Mountains National Park.

Lyme Disease is Most Common in 13 States

There's plenty of magnificent scenery along the AT, and although there's no need to be paranoid about the risk, it is important for hikers to know that part of that route is through areas where Lyme disease is endemic. The Centers for Disease Control and Prevention (CDC) says about 300,000 cases of Lyme disease were diagnosed in the U. S. in 2012, and 95% of those cases were reported from 13 states in the Northeast and Upper Midwest, from Virginia to Maine and then westward to Minnesota.

Although awareness of Lyme disease by the public and medical professionals is improving, there are two key factors in effective treatment: early recognition by an individual that he or she may have been infected, and prompt medical attention. According to the recent study, both of these may be a challenge for hikers on the AT, especially those who are engaged in a long trip on the trail.

A successful hike of any distance on the AT or any similar trail requires both preparation and determination, and once they're embarked on a long trek'especially a "thru-hike" of the entire trail, it would not be surprising for hikers to be determined to forge ahead despite not feeling quite up to par. When you're pushing your body to cover a lot of miles of trail every day, it's easier to shrug off a headache, muscle and joint aches, a stiff neck, fatigue, and even a fever as simply part of the physical price to be paid for a challenging hike.

Common Symptoms Can Make Diagnosis Difficult

It's the very general nature of those common symptoms of Lyme disease that make it so easy to overlook'or misdiagnose'and that makes the recognition of the single most distinctive indicator of this illness especially important. According to the CDC, more than 70% of patients diagnosed with Lyme disease have a red, expanding rash called erythema migrans (EM); this rash is by far the most common indicator of an infection. The rash may have a "bulls-eye" appearance, as shown in the photo below, or it may be uniformly red or reddish-blue. This link from LymeMD provides some additional details about the rash and other symptoms.

That information caused a group of medical professionals to ask an interesting question: If this distinctive rash is the most reliable indicator of Lyme disease, how many hikers on the AT would actually recognize that rash if they saw it? The answers obtained by the recent study weren't exactly encouraging.

During the project, 379 responses were collected from hikers "at three geographically separate locations at or proximate to the AT from June 2011 to May 2012." As part of the study, hikers were shown photographs of the rash typical of Lyme disease. Only slightly more than half (54%) recognized the rash and its significance. The study also provided one indication of the prevalence of the disease among hikers on the AT.

Why Spotting the Rash Is So Important

Six percent of the hikers in the study "had seen [such a rash] either on themselves or on another hiker while on the AT" and nine percent of the hikers stated that they had been diagnosed with Lyme disease by a healthcare practitioner. Of those diagnosed, only about a third had actually seen an embedded tick on their body, a further indication of the importance of the rash as a warning sign of an infection.



An example of the "EM" rash typical of Lyme disease. Photo by An example of the "EM" rash typical of Lyme disease. Photo by jongarrison via Creative Commons and wikipedia.

Awareness of Lyme disease and other tick-borne illnesses is important for anyone who ventures into the out-of-doors, not just hikers on the AT, so this study offers a timely reminder for all of us as we look ahead to warmer weather.

The photo to the right is one example of the signature rash, which the CDC says "begins at the site of a tick bite after a delay of 3-30 days (average is about 7 days). Rash gradually expands over a period of several days, and can reach up to 12 inches (30 cm) across. Parts of the rash may clear as it enlarges, resulting in a 'bull's-eye' appearance. Rash usually feels warm to the touch but is rarely itchy or painful."

You'll find more examples of the rash on page 13 of a helpful CDC publication on tickborne diseases at this link.

Finally, keep in mind that perhaps 30% of patients don't display a rash, so if you have other symptoms and have been in areas where ticks occur, don't hesitate to check with your health care provider.

Prevention and Treatment

Some tips for prevention and some good news are offered by the CDC: "most cases of Lyme disease can be treated successfully with a few weeks of antibiotics."That said, this is not an illness to ignore; left untreated, this disease can lead to serious complications.

The CDC has prepared a number of useful materials in an on-line "toolkit" available at this link, including a Lyme disease prevention fact sheet for hikers. This information is well worth reviewing before your next outdoor trip.

So, don't hesitate to enjoy a hike on the AT or anywhere else in the country. Just use common-sense techniques to reduce risks of tick bites, remove ticks promptly if you find them on your body, keep your eyes open for signs of a possible problem, and get medical help when it seems appropriate. This is one situation where "rash decision" to see a doctor could be a very good thing!

Perhaps you've had experience with Lyme disease, or know someone who has? If so, perhaps you'd like to share where it was contracted, if that's known, and any other advice for your fellow Travelers.