Bruce Trail News article

This article appeared in the Bruce Trail News - Spring 1994 (Ontario)
(Please note that the information may have changed since this article was written)

Lyme disease is not a serious problem on the Bruce Trail, but hikers, especially those who travel, would be wise to take precautions.

For Kathy, the summer of 1993 had already had its share of misfortunes. It started with a bad case of poison ivy that took forever to go away. Next came a rattlesnake bite while canoeing the Pickerel River. However, it was an innocent birding trip to Chincoteague, Virginia that put the crowning touch on her whole summer.

Thinking back on it, Kathy remembers lying down in the woods to get a closer look at a plant that she was trying to identify. A couple of days later, a small bull's-eye-shaped rash appeared on her side. At first she thought nothing of it, but when the rash continued to spread, she became concerned. And then she remembered something that she had read about earlier in the summer - Lyme disease!

As soon as she arrived home from Virginia, Kathy searched through her files and found a pamphlet on Lyme disease that someone had given her. Her rash matched the description of the Lyme disease rash perfectly. She took the pamphlet to her family physician who confirmed the diagnosis. The doctor prescribed 10 days of antibiotics, and soon the rash began to clear up.

Kathy was lucky. She obtained immediate medical treatment, avoiding the more unpleasant symptoms associated with the later stages of the disease.

Lyme disease was first diagnosed in 1975 in Lyme, Connecticut where 51 people came down with a mysterious arthritis-like ailment. Eventually, it was discovered that the disease was caused by a small, coiled spirochete bacterium called borrelia burgdorferi, or simply Bb. Bb is transmitted by the deer tick, otherwise known as Ixodes scapularis.

When a deer tick infected with Bb bites an animal or person, the bacterium may be transferred to that new host. Inside a person, Bb multiplies and can cause a variety of ailments ranging from simple flu-like symptoms, to arthritis, or even cardiac or neurological disorders.

By 1990 Lyme disease had been diagnosed in thousands of patients in at least 44 states, although it was much more prevalent in some areas than others. In Ontario the disease is not nearly so prevalent. This is because the deer tick, which is responsible for transmitting the Bb bacteria has a limited distribution in the province. In fact, there is only one known location within Ontario where the deer tick is considered common: Long Point on the north shore of Lake Erie.

So what is all the concern about? If you want to avoid getting Lyme disease, all you have to do is avoid Long Point, right? Well, not necessarily. In fact, of the 103 reported cases of Lyme disease that were contracted in Ontario since 1984, only 12 can be attributed to tick bites received at Long Point. The remaining 91 cases were contracted elsewhere in the province.

Now, if deer ticks are only found at Long Point, how is it that people are getting tick bites from other parts of the province? Well, to best explain this, we first need to take a look at the biology of the tick.

After hatching from the egg, each deer tick progresses through three stages, from larvae to nymph to adult. A blood meal is required before the tick can molt to each of the subsequent stages. To obtain a blood meal, the tick may climb tall vegetation and wait for a host to pass by close enough to attach itself. If the tick is successful, it will get its blood meal, drop off and molt to the next stage. Once the tick reaches the adult stage, it will mate and start the process over again.

Although the deer tick is able to live on a variety of warm-blooded animals, it does have a series of preferred hosts. Larvae and nymphs favour white-footed mice as hosts, while adults tend to parasitize white-tailed deer. Other, less common hosts include eastern chipmunks, striped skunks, raccoons and a variety of other birds and mammals.

If a tick happens to parasitize a migrating bird instead of a mammal, it could be transported hundreds of kilometres from its original starting point before it finishes taking its blood meal and drops off.

In order for a tick to become infected with Bb it must take a blood meal from an infected host. Some of the hosts that ticks feed on, such as the white-footed mouse, can act as reservoirs for Bb, harbouring it in their blood stream. Therefore, when an uninfected tick takes a blood meal from an infected mouse, it will become infected with Bb itself. The tick will then carry the bacteria through subsequent life stages and infect any new host it feeds upon.

The taking of a blood meal, however, is not a guarantee of transmission of Bb. According to Dr. Chuck LeBer, Senior Veterinary Consultant, Ontario Ministry of Health, the average feeding time required before the bacteria is transferred to a new host is between 36 and 48 hours. This means that a check of your body and clothing for ticks after a hike can be effective for preventing Lyme disease, even if the tick has already begun to feed.

Now we can piece together how a person might contract Lyme disease without visiting Long Point or any other endemic area (an area where the deer tick is reproducing in nature). If a tick parasitizes a bird, then it could be transported to other parts of Ontario before it finishes its blood meal and drops off. If that tick was already infected with Bb, or became infected with Bb from the bird, it would then have the potential to infect a new host. If by chance the tick finds a human host, the transmission of the bacteria could occur.

Fortunately, this movement of ticks on migratory birds appears to be restricted to single ticks only. In Ontario, there is no evidence to suggest that birds are contributing to the development of new deer tick populations in other parts of the province. In fact, when intensive searches are conducted in the vicinity of individual deer tick discoveries, no ticks other than the original have ever been found, with the exception of Long Point.

What are the odds of contracting Lyme disease in Ontario? It comes down to timing and location. To get Lyme disease, you have to come in contact with a deer tick that is infected with the Bb bacteria. And the most likely place where this could happen is at Long Point in midsummer. As well, not all ticks in an area carry the bacteria. At Long Point, for instance, only about one tick in 10 is infected with the Bb bacteria. Therefore, nine out of 10 ticks cannot give you Lyme disease.

The odds of getting Lyme disease elsewhere in the province appear to be quite low, particularly when you consider that there have only been 91 cases reported to the Ministry of Health since 1984, in a province of several million people. You are more likely to be in a car accident while driving to your favourite hiking spot than you are of getting Lyme disease on the hike.

Symptoms

Many early symptoms of Lyme disease resemble those of the flu. However, the bull's-eye shaped rash, or erythma migrans as it is called, is the most reliable symptom. It occurs within three to 32 days of the tick bite in 60 to 80 per cent of cases. The rash has the appearance of a red bull's-eye with a lighter coloured center. The size of the rash can range from five to 50 cm in diameter.

Other early symptoms of the disease include fatigue, headache, stiffness of the joints, stiff painful muscles, fever or swollen joints. If the disease progresses beyond the early stages, symptoms such as irregular heart beat, heart palpitations or neurological abnormalities can develop. Neurological symptoms include temporary drooping of the eyelids or comer of the mouth. In its most advanced stages, Lyme disease can be quite debilitating. The key is to begin treatment as soon as you recognize any symptoms.

Treatment in the early stages of Lyme disease usually consists of 10 to 14 days of oral antibiotics. However, treatment in the advanced stages can vary from long term oral antibiotics to antibiotics administered intravenously. Most patients who begin treatment in the early to intermediate stages of the disease make a complete recovery. However, even cases that go undiagnosed for long periods of time can be treated with some success.

Prevention

Precautions hikers should take for the prevention of Lyme disease depend on the area that they live or hike in. If you are hiking in an endemic area, such as Long Point, then you need to be more careful than when hiking the Bruce Trail.

Following is a list of suggestions to help minimize the risk of contracting Lyme disease. Note that these guidelines were designed for use in endemic areas, and should be tailored to match the risk of Lyme disease in your particular area.

1. Wear light-coloured, long-sleeved shirts and long pants. Tuck the pants into your socks and wear shoes rather than sandals or bare feet. Light-coloured clothing makes seeing ticks easier and also keeps you cooler.
2. Use a tick repellent or insect repellent that contains the active ingredient DEET
3. Avoid long grass or thick brush and walk in the middle of the trail, away from vegetation.
4. After you return from your hike, change out of your hiking clothes and check yourself carefully for ticks. Have someone check the areas of your body that you can't see. Check all members of your family including the kids and the dog. The tick is quite small, the nymph being about the size of a sesame seed. However, when the tick is engorged with blood, it can be as large as a raisin, and therefore much easier to spot.
5. Be aware of the early symptoms of Lyme disease and watch for them, especially the typical bull's-eye rash.

What should you do if you find a tick on yourself? First, remove it using a pair of fine tweezers. Grasp the tick at the point where it enters the skin and tug firmly but gently straight back. Be patient, the mouth parts of the tick are barbed and it may take some persuasion to get them out. If you are in doubt about doing this yourself, have a doctor do it for you. In either case, get the tick off as soon as possible. Remember, the longer you wait before removing the tick, the more time there is for any potential bacteria to be transmitted to your body.

Keep a record of the date of the bite and keep an eye out for a rash or other symptoms of Lyme disease. Save the tick for identification, preferably without killing it. There are other ticks within Ontario, such as the larger dog tick, which do not generally harbour Bb, and ticks can be tested to determine if they are infected with the Bb bacteria. Send your tick to your local public health unit or to the Lyme-Borreliosis Support Group of Ontario.

Lyme disease in Ontario is a concern for all outdoor enthusiasts. However, Lyme disease is not nearly as common in Ontario as it is in parts of the eastern United States. Your best defense against the disease is to learn how it is transmitted, what the symptoms are and most importantly, how to protect yourself from tick bites.

The chances of getting Lyme disease on the Bruce Trail are quite low, and concern over contracting the disease should not be allowed to interfere with your enjoyment of the outdoors. Take a few simple precautions, relax and enjoy your hike.