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Lyme disease is caused by bacteria called Borrelia burgdorferi. This bacterium is carried by certain ticks, and spreads to the host when the tick bites. The bacterium is normally found in small animals such as mice, squirrels, chipmunks, shrews, etc.
Lyme disease in humans can have a range of effects from rashes and flu-like symptoms to more serious symptoms including arthritic, cardiac and neurological effects. It can often be effectively treated, especially if detected in the early stages.
Lyme disease is an occupational concern for people who work outdoors. Any person who spends time outdoors is also at risk.
In the United States, Lyme disease is the most common "vector borne" disease. Vector is the term for any insect or arthropod that carries and transmits a disease pathogen (virus, bacteria, etc.).
Ticks usually live in woods or tall grasslands in Canada, the United States, Europe and Asia. Ticks infected with Borrelia burgdorferi spread the disease when they feed on blood from the host. Ticks cannot fly - they hang onto small bushes or tall grasses and are usually found close to the ground. They wait for an animal or person to pass near them and when the animals or person make contact, the ticks attach themselves to the skin to feed.
In North America, Lyme disease is transmitted (spread) mainly by two species of ticks:
The Public Health Agency of Canada (PHAC) also states that pets, especially dogs, can get Lyme disease, but there is no evidence that pets can spread the infection directly to humans. However, pets can carry infected ticks into the home or yard.
Tick bites are usually painless and most people do not know they have been bitten. Signs and symptoms of Lyme disease vary greatly from person to person.
Symptoms often include:
A typical sign of infection is an expanding rash, sometimes referred to as a "bull's eye" rash because it may have rings spreading from the bite site (known as erythema migrans). It is important to note that rashes without the bull's eye may occur, and that rashes do not appear in every case of Lyme disease infection. If a rash is to appear, it usually appears in 7 to 14 days, but may appear three days to a month after infection. The rash can last up to 8 weeks. It can be warm to the touch, but may not be painful or itchy. Images of rashes are available from PHAC.
Additional symptoms include:
If untreated, a condition called late disseminated Lyme disease may occur. PHAC reports symptoms include recurring arthritis (muscle and joint pain), nervous system and/or neurological problems. Symptoms can also include numbness and/or paralysis (unable to move parts of the body). Deaths from Lyme disease are rare but may occur.
Lyme disease can be difficult to recognize, and it has been confused with other diseases. It is important for people to consult with their doctor if they feel it is possible that they have Lyme disease.
In most cases, yes. Antibiotics can effectively treat Lyme disease, especially when treatment begins early. Cases that reach the later stages of the disease, however, can be difficult to treat and some symptoms can persist.
PHAC reports that removing the tick within 24-36 hours usually prevents infection.
Many people who develop the disease do not remember seeing ticks or being bitten. Tick bites commonly occur from May to September in North America, although blacklegged ticks can be active most of the year. Ticks sometimes move around on the body but they usually attach themselves to the skin and stay in one place. Before feeding, ticks look like small, brown scabs or freckles. After feeding, ticks may swell considerably, and could be as big as a raisin or a small grape.
Follow the link for more information about blacklegged (deer) ticks (including photographs) from the Government of Canada.
Yes and no. There are areas in which the bacteria is endemic meaning the disease is established and present more or less continually in that community.
In Canada, blacklegged tick populations have been confirmed or are growing in the following areas:
However, it is important to note that ticks (including those that are infected with the Borrelia burgdorferi bacteria) can be spread by birds, in particular songbirds that feed off the forest floor. Because these birds are migratory, there is the potential for new populations of the bacteria to spread across the country. This fact means that you do not have to be in an endemic or high-risk area to be at risk of contacting ticks and the disease.
When a person becomes infected, the body creates antibodies to protect itself from the bacteria. Certain blood tests are available to measure these antibodies. However, sometimes a "false negative" test can result if there are not enough antibodies in the blood for the tests to detect accurately. A doctor should also do a complete medical examination and get information about your activities in order to make a clinical diagnosis for Lyme disease.
Many occupations may be at risk, including forestry, farming, veterinarians, construction, landscaping, ground keepers, park or wildlife management, and anyone who either works outside or has contact with animals that may carry the ticks (including domestic animals like dogs, cats, goats, cows, horses, etc.)
Similarly, any person who spends a lot time outdoors (hiking, camping, birding, golfing, hunting, fishing, etc.), especially in grassy or wooded areas may also be at risk.
In areas where ticks are found, people should know about the risk of Lyme disease and should take precautions to protect themselves. Be aware of the signs and symptoms of Lyme disease so it can be detected and treated promptly.
The Public Health Agency of Canada has issued a public health reminder stating "Lyme disease is a serious illness that's present in Canada and spreading." PHAC has also prepared a Lyme disease tool kit which provides material to raise awareness and educate.
Keep the lawn and yard well maintained to prevent ticks from living near the home or workplace.
Add a badge to your website or intranet so your workers can quickly find answers to their health and safety questions.
Although every effort is made to ensure the accuracy, currency and completeness of the information, CCOHS does not guarantee, warrant, represent or undertake that the information provided is correct, accurate or current. CCOHS is not liable for any loss, claim, or demand arising directly or indirectly from any use or reliance upon the information.