Lyme disease (LD) is an infection caused by Borrelia burgdorferi, a type of bacterium that is spread by the bite of infected deer ticks. Untreated, the bacteria can travel through the bloodstream infecting various organs causing a wide variety of possible problems. While Catamount Trail skiers cannot catch LD during the winter, those who volunteer to work on trails in the fall do incur some risk of contracting it. Having a clear picture of LD will minimize the risks of getting it.
What is the Risk of Getting Lyme Disease?
The incidence of LD is rapidly increasing. For the U.S. in 2006, Vermont had the thirteenth highest rate of LD at 16 cases per 100,000 residents. Statistics like this can be hard to fathom. For perspective, here are the national rates of other common mishaps:
- Number of people injured in car accidents in 2005…………………. 911 per 100,000
- Number of people killed in car accidents in 2005………………….. 14.6 per 100,000
- Yearly cases of food poisoning……………………………………. 300-1300 per 100,000
- Yearly deaths from food poisoning………………………………………….. 4 per 100,000
- Injuries per single day of skiing……………………………………………… 72 per 100,000
These data indicate that the risk of contracting LD is much less than receiving injuries from daily activities such as eating and driving. Further, a skier is much more likely to be injured in a single day of skiing than he is to get LD in an entire Vermont tick season.
How Can I Lower My Risk of Getting Lyme Disease?
Geography matters. According to the Centers for Disease Control, the southern half of Vermont poses a medium risk for LD exposure while the northern half poses a low risk. There is some comfort in evidence that higher altitude areas where much of the Catamount Trail runs have both lower deer tick densities and lower infection rates of the ticks with the disease. Ticks become inactive at temperatures below 35 degrees F making cold fall days particularly attractive for doing trail work in areas with tick infestations. For trail workers, it is reassuring that the fall is much safer than spring and summer with 80% of LD cases contracted in the months May through August.
To minimize tick bites while working in infested areas, the Vermont Department of Health advises:
- Wear long pants and long-sleeved shirts to minimize skin exposure to ticks.
- Tuck your pants into your socks to form a barrier to tick attachment.
- Wear light-colored clothing to make ticks on your clothing easier to see.
- Check for ticks, looking particularly for what may look like nothing more than a new freckle or speck of dirt.
- Use tick and insect repellents containing DEET or permethrin to help protect against Lyme disease. DEET-containing preparations should be used sparingly, following the label instructions carefully.
Deer ticks are tiny and often go unnoticed. For example, nymphal deer ticks, the most common transmitters of Lyme disease, are about 2mm, or the size of this dot (·); see photo below. If you get bitten by a tick, follow these steps to safely remove it:
- Using a pair of pointed precision tweezers, grasp the tick by the head or mouthparts right where they enter the skin. DO NOT grasp the tick by the body. Alternatively, there are plastic tick removal devices commercially available.
- Without jerking, pull firmly and steadily directly outward. DO NOT twist the tick out or apply petroleum jelly, a hot match, alcohol or any other irritant to the tick in an attempt to get it to back out.
- Clean the bite wound with disinfectant.
- After removal, a small red spot may appear. This is just an allergic reaction to the bite, nothing to be concerned about.
An infected tick does not transmit the bacteria until it has been attached for about 36-48 hours. Therefore, one of the best defenses against infection when you have been in a risky environment is to examine yourself at least once daily and remove any ticks before they become engorged (swollen) with blood. Generally, if you discover a deer tick attached to your skin that has not yet become engorged, it has not been there long enough to transmit the LD bacteria. If a tick has been attached for 36 hours or more, a single dose of antibiotic is very effective at preventing disease if started within 72 hours of discovery and removal of the tick. After a tick-bite be alert in case any symptoms do appear.
What are the Symptoms of Lyme Disease?
The first symptom is usually an expanding rash called erythema migrans (EM). It has the following characteristics:
Usually starts at the tick-bite
- Solid red expanding blotch or central spot surrounded by clear skin that is in turn ringed by an expanding red rash (like a bull’s-eye)
- Appears about 7 days (range 3-32 days) after the bite
- Average diameter 5 to 6 inches
- Lasts about 3 to 5 weeks
- Usually not painful or itchy
For photos of this rash, guide your web browser to: http://www.aldf.com/EMPoster.shtml
Other symptoms which could signal first stage LD, even if the rash never developed, include headache, fever, fatigue, or joint pains in the first month following the deer tick bite.
If you think you have LD contact your physician immediately. The EM rash, which occurs in up to 90% of reported cases, is a specific feature of LD and requires immediate treatment. Even in the absence of an EM rash, diagnosis of early, or Stage 1, LD should be made on the basis of symptoms and evidence of a tick bite. Blood tests can often give false results if performed in the first month after initial infection; later on the tests are somewhat more reliable, though not perfect. If diagnosed and treated early with antibiotics, LD is readily cured. In its later stages LD can also be treated effectively, but some patients may have symptoms that linger for months or even years following treatment. Rarely, LD causes permanent damage. Later stages of LD have varied symptoms:
Stage 2 (weeks to months):
- Two or more rashes not at site of bite
- Migrating joint pains
- Stiff, aching neck
- Facial paralysis
- Tingling or numbness in extremities
- Large lymph nodes
- Abnormal heart beat
- Severe fatigue
Stage 3 (months to years):
- Pain and swelling of one or two large joints
- Disorientation, confusion, dizziness, short-term memory loss, inability to concentrate
- Numbness in arms/hands or legs/feet
The risk of contracting LD in Vermont is a real but manageable threat. We manage all sorts of risks in our everyday lives: we wear seat-belts when driving, make sure poultry and ground meat are well-cooked, ski in control at all times, and wear helmets when bicycling. I believe that the possible health risks of contracting LD are far out-weighed by the health benefits of exercising in the outdoors. So, when you are outdoors during non-winter months, take the above precautions to avoid LD and stay healthy. I hope to see you on the trail this fall and winter.
Reference: http://healthvermont.gov/prevent – Wilderness Medicine, 5th Edition, Paul S. Auerbach
This article was originally printed in the Catamount Trail Newsletter and was authored by Dr. George Terwilliger, an ER physician who lives in Brattleboro and is a lifelong Vermont resident. He is an avid backcountry skier and has skied many sections of the Catamount Trail.