As you and your dog stroll through the tall grass or low shrubbery of your favourite forest path, you might be picking up more than the fresh scent of balsam fir. Blacklegged ticks (also known as deer ticks) are just waiting to hitch a ride-on both of you, and if a particular tick has fed on a bird or an animal with Lyme disease, that tick can pass Lyme disease on to you or your dog.
There are several species of ticks, but only blacklegged ticks can carry Lyme disease, and few of them actually do. In Nova Scotia, blacklegged ticks are considered established in parts of five counties: Pictou, Lunenburg, Halifax, Shelburne and Yarmouth. Since 2002, 67 cases of Lyme disease have been reported in the province. Most people and their pets are bitten by dog ticks, which do not carry Lyme, so knowing the difference between dog ticks and blacklegged ticks could ease your mind (see below).
"Lyme disease is an infection caused by the micro-organism Borrelia burgdorferi," says Dr. Lynn Johnston, division chief for Infectious Diseases at the QEII Health Sciences Centre in Halifax. Symptoms of early Lyme disease, which occur from seven to 10 days after the bite, are fever, fatigue and muscle aches and pains, which can make it hard to distinguish from any number of other illnesses. A key indicator, however, is an erythema migrans (EM) or a "bull's eye" rash.
Lab testing is not required to diagnose early Lyme. "In the early stages, the body has not had time to form antibodies; this could take up to six weeks after the initial infection," says Dr. Johnston. "Also, EM has a characteristic appearance, so a clinical diagnosis can be made on this basis."
Patients are treated with an antibiotic; this treatment has a success rate of more than 90 per cent, and patients usually recover in a matter of weeks.
For later-stage Lyme disease, when the EM rash may no longer be evident, physicians order a blood test to look for antibodies to the disease.
If Lyme disease goes untreated, it could spread from the skin to the blood and other areas of the body, such as the central nervous system or joints. Some people experience chronic fatigue symptoms, even after Lyme disease has been successfully treated and the B. burgdorferi is no longer present.
Dr. Johnston says some people have coined the term "chronic Lyme" to describe chronic non-specific symptoms such as pain and fatigue, with the mistaken belief that active Lyme disease is present. There is no good laboratory evidence of this.
The best treatment is prevention: to prevent tick bites when you're walking in an area where ticks may be present, wear enclosed shoes and light coloured clothing with a tight weave. Ensure that your shirt is tucked in and tuck the legs of your pants into your socks. Spray your clothing and exposed skin with an insect repellent that contains DEET (but note that DEET should not be used on children under seven months old; you can find Health Canada's guidelines for DEET use at hc-sc.gc.ca).
If you find a tick on yourself or your pet, you can go to your family doctor or vet to have it removed, or remove it yourself (see below right) - but beware of some commonly-touted methods for removal. Andrew Hebda, curator of zoology at the Nova Scotia Museum of Natural History, cautions people not to put Vaseline, oil, or a lit match on the tick. "Ticks breathe through openings along their sides. If those openings are blocked, the tick may come off, but not before it empties its stomach contents into your flesh." He also says not to pull too quickly or to twist the tweezers because the palps (mouth parts) could break off and remain in your flesh. This could cause an infection. It could also make identification of the type of tick more difficult.
Until September of last year, a province-wide passive survey was being conducted by the Nova Scotia Department of Health and Wellness; the public, veterinarians and physicians were welcome to submit specimens. The Department of Health and Wellness no longer needs to receive ticks for testing or surveillance purposes. The focus has now shifted from both passive and active surveillance to solely active fieldwork, studying areas where tick populations are expanding. Department of Natural Resources officials now visit sites from which multiple ticks have been submitted and check squirrels, mice, and other small mammals for ticks.
Know your ticks
- Larger than blacklegged ticks
- Milky markings on reddish-brown shield
- Short, thick palps (mouth parts)
- Festoons (blocks) along perimeter of back
- No milky markings, small black shield
- Long, narrow palps
- No festoons on perimeter of back
- Do a tick check on yourself and your pet after a walk in tall grass or low shrubbery
- Remove the tick within 24 hours
- Use clean tweezers or a tick removal tool
- Grasp the tick's body as close to the skin as possible
- Pull slowly to allow the mouth parts to fold together and come out
- Wash the area thoroughly and apply an antiseptic
- f infection occurs, see a doctor (or a vet)
To find out more about Lyme disease, visit the Nova Scotia Department of Health and Wellness site at gov.ns.ca/hpp/cdpc/lyme.asp.