Lyme Disease
- Lyme bacteria have not been found yet in Alberta but Lyme disease is being reported with increasing frequency and geographic range throughout Canada and the United States.
- People in Alberta should be aware of the possibility that Lyme disease could appear here.
- Generally people do not die from Lyme disease and it can be treated readily if diagnosed early.
People who travel to high risk areas in the United States, B.C. and Ontario should take precautions. Veterinarians should consider Lyme disease in differential diagnosis of certain clinical conditions.
- This page provides information about the disease and its recognition, treatment and prevention.
Where is Lyme disease found?
Lyme disease has been recognized in Europe since the early 1900s. However, within the last 20 years it has been reported with increasing regularity throughout the world, particularly in the United States. It has reached epidemic proportions in the northeast (Massachusetts to New York), and north-central regions (Wisconsin, Minnesota), with an increasing number of cases along the Pacific northwest (northern California to Washington). Most states have reported some cases of Lyme disease.
In Canada, cases of Lyme disease have been reported in many provinces and in a variety of species. Ontario and British Columbia have areas where the disease is established and several other provinces have had sporadic cases.
How is Lyme disease transmitted?
There is much to be learned about how Lyme disease is transmitted in nature. The disease is caused by a tiny spiral-shaped bacterium, Borrelia burgdorferi. Infection of humans usually occurs during the summer months from May to August and after a bite by an infected arthropod. In most cases the arthropod is a tick. Under laboratory conditions, horseflies, deer-flies, and mosquitos also may carry the bacteria but their role in transmitting Lyme disease in the wild currently is unknown.
The most common ticks carrying Lyme disease in eastern and western North America are NOT found in Alberta; however, some of the tick species found in the province can successfully pass on the bacteria in laboratory situations. Ticks on migrating birds also may carry the bacteria and some common bird species are potential hosts for Lyme bacteria. All aspects of Lyme disease, including methods of transmission, are being intensively investigated.
In Alberta, Lyme disease is most likely to occur in the foothills, mountains, and aspen parkland areas where arthropods are most common. The tick found on moose in the winter is not likely to carry the bacteria but ticks on rabbits, hares, ground squirrels, white-footed mice, deer, elk, bighorn sheep, and mountain goats could be involved in the cycle.
Small rodents, usually white-footed mice or deer mice, are the best hosts for Lyme bacteria. Larval ticks pick up the bacteria when they take blood from infected mice. The tiny seed ticks moult into bigger ticks (nymphs) which attach to vegetation and are picked up by animals passing by. These animals could be ground squirrels, rabbits, hares or people. After feeding, the nymphs drop off, moult to adults, and then attach to bigger animals, such as deer. Thus the greatest chance of people being infected occurs when they walk bare-legged through brush and tall grass in spring and summer when tick nymphs are most active.
Remember, the number of ticks, if any, carrying Lyme disease in Alberta probably is very small. In a survey of ticks collected in southern Alberta in 1991, no infected ticks were found nor was there any evidence of infection in dogs, deer, or mice that had been exposed to ticks. In addition, in order to transmit the disease, an infected tick must have its mouthparts buried in your skin for at least 18 to 24 hours. Thus, daily checks and removal of ticks should virtually eliminate any risk of transmission in Alberta.
What to look for
In many cases Lyme disease is recognized as a red rash starting at the tick bite and spreading out, often as a growing circle. This rash can start 3 to 30 days after the bite. (A swollen red area that appears immediately after the tick bites is likely a reaction to the tick and is NOT Lyme disease.) The rash may be accompanied by fever, chills, headache, fatigue, and swollen lymph glands.
In some cases, Lyme disease results in neurological and muscular problems weeks or months after the original infection. More serious ailments such as recurrent meningitis, heart problems, and arthritis may be present for years. In addition, infection in pregnant females has been associated with abortion and abnormal development of the foetus in humans and domestic species.
Arthritis and neurologic disorders also have been reported in horses, cattle, and dogs. Fever and sudden or intermittent lameness are early signs of Lyme disease in domestic species. Neurologic signs were seen in wild mice trapped in Wisconsin but clinical signs in other wildlife species are unknown.
Can Lyme disease be treated?
YES, particularly in the early stages. Borrelia bacteria can be killed with intramuscular injections of penicillin or tetracycline. Penicillin also is effective in resolving the arthritis and muscular problems seen later in some infections. There are very few reports of experimental treatment of Lyme disease in domestic or wildlife species.
Who is at greatest risk?
People who are active outdoors are most likely to contact ticks and other arthropods. This includes children, anglers, hikers, canoeists, farmers, tourists, and persons involved in forestry and wildlife occupations (such as loggers, trappers, and biologists). Anyone who spends time in tall grass, brush or forested areas should shower and/or make a thorough daily check of your body (particularly head, neck and groin regions) for ticks or later, the characteristic red rash.
People who travel to areas of the United States with epidemic Lyme disease are at greater risk than those who stay in Alberta. In addition, people who are active with hunting dogs in areas of good tick habitat may be at risk, as are their dogs.
How can I avoid Lyme disease?
You could stay inside or away from biting arthropods! However, for most people that is unrealistic (and very boring). Here are some precautions you can take without limiting your time outdoors.
- Don't walk bare-legged in tall grass, brush, or woods where ticks might be found.
- If you do go into such areas, cover up as much as possible. Wear a long- sleeved shirt, long pants, long socks (pulled up over pant legs), enclosed shoes or boots, and a hat.
- Wear light colours (ticks are dark and easier to see against a light background).
- Remove clothes and do a daily 'tick check' after being outdoors. Some ticks are quite small - the size of a pin-head or freckle.
- Regularly check children and pets after they have been outside in 'ticky' areas. Carefully remove all ticks.
What if I find a tick embedded in my skin?
First, DO NOT SQUASH IT! If it is infected, the bateria may go directly into your skin. Also, squeezing an infected tick may force bacteria out of the mouthparts, and into the tick bite – YOU.
The best way to remove a tick is to grasp it gently with tweezers as close to its mouth as possible (the part sticking into your skin) Slowly pull the tick straight out - do not jerk or twist it. Note the rumoured remedies like matches, cigarettes, or vaseline DO NOT WORK and may cause an infected tick to pump bacteria into the wound. Check the tick bite area for at least two weeks. If a red rash appears, take the tick (if possible) and go to a doctor.
Summary
- Lyme disease can be serious but rarely is fatal in humans.
- The bacteria has not been found yet in Alberta but could appear here in the future.
- Lyme disease is treated readily in humans if identified early.
- If you see a growing red rash 10 to 12 days after being bitten by a tick, see a doctor.
- Travellers, outdoor enthusiasts, and children may be at risk during the summer but simple precautions can reduce the risk.
For further information, please contact your health region's public health service.
