Lyme Disease
Alberta perspective
- In July 2007, Ixodes pacificus ticks were found on dogs in the Edmonton area. This is a species known to carry Lyme disease. Two of the 10 ticks found were infected with Lyme bacteria. These adult ticks may have been carried in by migrating birds from west of the Rockies (British Columbia).
- A surveillance program is ongoing and ticks from dogs can be submitted by veterinarians for testing for Lyme disease.
- 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 emerge here.
- Generally, people do not die from Lyme disease and it can be treated readily if diagnosed early.
Watch this Alberta Top Doc video on ticks
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.
- For more information visit the Centers for Disease Control (CDC) website.
In Canada, cases of Lyme disease have been reported in many provinces and in a variety of tick species. Southern and eastern Ontario, southeastern Manitoba, parts of Nova Scotia and British Columbia (Vancouver Island and lower Fraser Valley) have areas where Lyme bacteria are established in ticks.
- For more information visit the Public Health Agency of Canada (PHAC) website.
A Lyme-endemic area is defined as an area where all three feeding stages of the tick (larva, nymph and adult) are present on local animals or in the environment for at least two consecutive years.
How is Lyme disease transmitted?
The bacterium that causes Lyme is carried in mice, squirrels, birds and other small rodents and is transmitted to a tick when the tick bites the animal. It is then transmitted to humans when they are bitten by an infected tick. In order to transmit the disease, an infected tick must have its mouthparts buried in your skin for at least 18–24 hours. Thus, daily checks and removal of ticks should virtually eliminate the risk of acquiring the infection.
Humans cannot transmit the bacteria to other humans. While ticks can transmit the bacteria to cats and dogs, there is no evidence that pet-to-human transmission can occur.
In Alberta, the highest risk of being bitten by a tick occurs during the summer months from May to August. Areas at higher risk include the foothills, mountains, and aspen parkland areas where ticks are more common. These ticks attach to vegetation and are picked up by people walking bare-legged through brush and tall grass when tick nymphs are most active.
HOWEVER, the chances of being bitten and subsequently infected are considered low in areas where infected Ixodes tick populations are not established, such as Alberta.
The most common ticks carrying Lyme disease in eastern (Ixodes scapularis) and western (Ixodes pacificus) North America are not commonly found in Alberta. Results of an on-going survey of ticks collected in Alberta, while not yet published, reveal that small numbers of the ticks that can transmit Lyme disease have been found in the province, but do not yet appear to be an established population.
Also, it has been shown in research that up to 12 per cent of ticks that are left behind by migratory birds may be infected with Lyme bacteria. All aspects of Lyme disease including methods of transmission are being closely investigated in Alberta.
What are the symptoms of Lyme disease?
In 60–80 per cent of cases, about 3–30 days after the tick bite, a red circular rash (called erythema migrans or EM) occurs starting at the tick bite site spreading outwards. The center of the rash may clear as it enlarges, resulting in a bull's-eye appearance. It may be warm but is not usually painful. Some patients develop additional EM lesions in other areas of the body after several days.
- The rash may be accompanied by fever, chills, headache, fatigue, and swollen lymph glands.
- A swollen red area that appears immediately after the tick bites is simply a reaction to the tick and is NOT likely Lyme disease.
If untreated, the second stage of illness can occur with symptoms including multiple EM, arthritis, heart palpitations, fatigue, generalized weakness and central/peripheral nervous system disorders. Many of these symptoms resolve, even without medical treatment.
After a few months, about 60 per cent of untreated cases may have recurrent arthritis, particularly the large joints (e.g., knees). A further five per cent of untreated cases may develop chronic neurological symptoms such as shooting pains, numbness or tingling in the hands or feet, and problems with concentration and short term memory that may be present for years.
Infection in pregnant females has been associated with miscarriage and abnormal development of the fetus.
How is Lyme disease diagnosed?
Lyme disease is diagnosed by a physician based on clinical symptoms, the patient’s history, and laboratory tests when needed. It is recommended that only individuals with symptoms and history of exposure to ticks or living in or visiting an area with known endemic tick activity, be tested for Lyme disease. Test results should always be evaluated in the context of the patient’s history of exposure and symptoms.
Testing for Lyme disease in Alberta follows a two-tiered approach:
- Enzyme immunoassay (EIA) is very sensitive (almost everyone with Lyme disease will test positive) but lacks specificity (some people who do not have Lyme disease may test positive).
- Western Blot test is very specific (it will usually be positive only if a person has been truly infected). This second test is used so that people are not diagnosed with Lyme when they do not have it.
Can Lyme disease be treated?
YES. Lyme disease can be treated, particularly in the early stages. Individuals treated with antibiotics in the early stages of infection usually recover completely. Those diagnosed and treated in later stages may have persistent or recurrent symptoms. The benefits of long-term antibiotic treatment have not been shown to outweigh the risks of complications from them.
Just because a person has persistent symptoms from what they think is Lyme disease, does not necessarily mean they have Lyme disease. Co-infection or new infection with other organisms (viruses, bacteria, parasites and fungi) may be the cause of symptoms that persist or recur.
Recent studies have shown that there are no negative effects on the developing fetus and pregnant women infected with Lyme can be treated with appropriate antibiotics.
Who is at greatest risk?
People who are active outdoors are more likely to come into contact with 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).
People who spend time in tall grass, brush or forested areas should do a daily check of their body (particularly head, neck and groin regions) for ticks and thereafter watch for, and report, any symptoms of Lyme disease.
People who travel to areas of the United States with endemic Lyme disease are at greater risk than those who stay in Alberta. In addition, people who are active with hunting dogs in areas where ticks are endemic may be at risk, as are their dogs.
How can I avoid Lyme disease?
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).
- Spray clothing and exposed skin with an insect repellent that contains DEET. Read and follow the manufacturer's directions for safe use.
- Remove clothes and do a daily "tick check." Some ticks are quite small – the size of a pin-head or freckle.
- Regularly check children and pets after they have been outside in risk areas. Carefully remove all ticks.
What if I find a tick embedded in my skin?
The best way to remove a tick is:
- With tweezers, gently grasp its head and mouth parts as close to your skin as possible.
- Slowly pull the tick straight out – do not jerk or twist it.
- Clean your skin with soap and water. You may disinfect the bite area with alcohol or a wound disinfectant.
- Save the tick in a clean, empty pill bottle or double zip-lock bag so that it can be submitted for testing IF you become symptomatic (testing of ticks without evidence of clinical illness is not recommended).
DO NOT SQUASH IT!
If it is infected, the bacteria may go directly into your skin. Also, squeezing an infected tick may force bacteria out of the mouthparts and into your skin.
Remedies like matches, cigarettes, or petroleum jellies DO NOT WORK and may cause an infected tick to release the bacteria into the wound.
Check the tick bite area for at least two weeks. If a red rash appears, take the tick (if available) and seek medical attention.
- For more information, please contact Health Link Alberta.
