Lyme disease is an infectious disease caused by the bacteria Borrelia burgdorferi and affects horses, humans and many other animals. Although Lyme disease in horses is quite common for animals living in high-risk areas, equine Lyme disease is not easy to identify, since fewer than 10% of horses show any symptoms.
Tick - Carrier of Lyme disease affecting horses and humans
The Government of Canada engages in surveillance activities to determine the number of cases of Lyme disease and the locations of tick populations to keep people informed so they can protect themselves, their horses and pets from contracting the disease.
© 2012 by Artist Name
Symptoms vary from horse to horse, but an equine with Lyme disease may show an unexplained reluctance to move, as if sore all over, and/or a transitory lameness that cannot be ascribed to any specific cause. Joint swelling may also be apparent in some horses.
The Government of Canada engages in surveillance activities to determine the number of cases of Lyme disease and the locations of tick populations. It does this in partnership with:
- provincial and territorial public health organizations
- health authorities
- other experts
Surveillance is done in 3 ways:
- reporting of human Lyme disease cases by Provincial and Territorial public health organisations
- voluntary submission of ticks collected from people and pets including horses by doctors and vets (known as passive tick surveillance)
- studies in the field to collect ticks from the environment (knows as active tick surveillance)
Locations where both ticks and Lyme disease have been confirmed over multiple years of active field surveillance are called known endemic areas. Confirmation is based on:
- active field surveillance revealed the presence of all life stages of the ticks at multiple visits over more than one year
- detection of the Lyme disease pathogen in ticks or animals collected from the site
A suspected endemic area is the same as an endemic area except that the ticks and Lyme disease pathogen have not yet been found in more than one year.
Locations where tick vectors of Lyme disease have been detected by active surveillance are considered to be risk areas. The presence of Borrelia burgdorferi does not need to be confirmed in samples (tick or animal) for an area to be considered a risk area.
Through surveillance, the Government can identify trends in the numbers of Lyme disease cases and where in Canada there is a risk of getting Lyme disease. The greatest risk occurs where ticks that carry the Lyme disease-causing agent are found. Surveillance in recent years indicates that established populations of blacklegged ticks are spreading. However, while tick numbers are increasing in eastern and central Canada, the British Columbia Ministry of Health indicates that this is not the case in British Columbia.
British Columbia
In British Columbia (B.C.), known and suspect endemic areas for Lyme disease are found on:
- Vancouver Island
- Southern Mainland
- Coast of British Columbia facing Vancouver Island
Risk areas include:
- River valleys across the southern part of the province
The B.C. Ministry of Health has reported a plateau in the number of infected tick populations in the past decade. This contrasts to the spread seen in the rest of Canada. This is due to:
- the western blacklegged ticks spread into B.C. much earlier than the blacklegged ticks found in central and eastern Canada
- far fewer western blacklegged ticks being infected with the Lyme disease bacterium than blacklegged ticks found in central and eastern Canada
Manitoba
In Manitoba, known or suspect areas for Lyme disease are the:
- west side of Lake of the Woods
- Pembina escarpment, including Pembina Valley Provincial Park
- St. Malo region
- Vita/Arbakka region, including the Roseau River
- Beaudry Provincial Park
- Assiniboine River
- areas next to the Agassiz and Sandilands provincial forests
Risk areas include:
- parts of southern Manitoba along the border with the United States from south of Brandon to Lake of the Woods
- some areas around Winnipeg
Ontario
In Ontario, known endemic areas for Lyme disease are:
- Point Pelee National Park
- Rondeau and Turkey Point provincial parks
- Long Point peninsula, including Long Point Provincial Park and the national wildlife area
- Wainfleet bog near Welland on the Niagara peninsula
- Prince Edward Point
- parts of Thousand Islands National Park
Risk areas include:
- locations around Kingston
- along the St. Lawrence Valley to the border with Quebec and northeast towards Ottawa
- western Ontario in the region of Lake of the Woods
- Pinery Park on the shore of Lake Huron
- Rouge Valley region of eastern Toronto
Quebec
In Quebec, known endemic areas for Lyme disease are found in:
- Montérégie (south of Québec)
Risk areas include:
- much of Montérégie
- parts of Estrie
- parts of central Québec
New Brunswick
In New Brunswick, known endemic areas for Lyme disease are:
- the Millidgeville area of Saint John
- North Head on Grand Manan Island
Nova Scotia
In Nova Scotia, known endemic areas for Lyme disease are:
- Halifax Regional Municipality
- areas in the counties of Lunenburg, Shelburne, Yarmouth, Pictou and Queens
Possible risk areas are locations around these endemic areas.
Other areas
As ticks attach themselves to birds, they can be found in areas across Canada, other than those noted above. Ongoing surveillance by the Government helps identify the spread of blacklegged tick populations in Canada.
Because localized tick populations can spread, it is difficult to define the geographic limits of a population. Canadians living or visiting areas next to established tick populations are advised to take precautions against ticks.