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Lyme Disease

Last updated:  May 8, 2023

What is Lyme Disease?

Lyme disease is an infectious disease caused by the bacterium Borrelia burgdorferi. Lyme disease can be spread to humans by infected blacklegged (deer) ticks (Ixodes scupularis). Ticks can become carriers of Lyme disease by feeding on infected animals, birds and rodents. 

Lyme disease is an ongoing concern in Canada, especially since people can be unaware that a tick is feeding on them. In addition, the prolonged incubation period (i.e. time difference between infection and onset of symptoms), may lead to a misdiagnoses or being undiagnosed. Therefore, it is important to remain tick smart and prevent tick bites.  

Will I get Lyme Disease if I am bitten by an Infected tick?

An infected tick that is attached to an individual for longer than 24 hours carries a higher risk of transmitting Lyme disease compared to an infected ticket that is attached to an individual for less than 24 hours. Improper removal of a tick can also increase the risk of infection. Use this resource to learn how to safely remove a tick.  

What are the Symptoms of Lyme Disease?

Individuals with Lyme disease may experience the following symptoms:  

  • General flu-like symptoms (fever, chills, headache, fatigue) 
  • Erythema migrain (EM) rash commonly called a “bull’s eye rash 
  • Swollen lymph nodes 
  • Neurological issues (tingling of limbs, dizziness) 
  • Arthritis – especially of larger joints like the knees 
  • Facial paralysis 

NOTE: Symptoms may take weeks to develop following an infected tick bite. If you have recently been bitten by a tick and are feeling unwell, seek medical attention. Early treatment is key to preventing severe or prolonged illness.  

How is Lyme Disease Monitored?

Active surveillance for Lyme Disease and blacklegged ticks is conducted nationally. In Ontario, a current risk map is maintained to summarize public health’s active surveillance efforts. There are also passive surveillance efforts like With risk areas expanding due to climate change, it is important to remember the fundamentals of staying tick smart and preventing bites as much as possible.  

Where can I get more information about Lyme Disease?