Lyme Disease

Lyme disease is a vector-borne disease. It is a bacterial disease transmitted to humans by an infected tick.

The bacterial infection is mostly caused by Borrelia burgdorferi. It cycles between wild animal hosts and the vector (ticks). Ticks become infected after feeding on small, infected mammals and birds. The disease is not transmissible between people - humans are considered dead-end hosts. The black legged tick (I. Scapularis) is the main tick vector in the United States but many tick species have been involved in transmission globally and there are other Lyme-like Borrelia as well.

Lyme disease is the most common vector-borne disease in the temperate zones of the northern hemisphere. Current case reports in Europe would suggest a gross underestimate of the disease. The distribution of ticks is likely to spread northwards with climate change. See ECDC's tick surveillance maps.

Ticks known to carry the bacteria are commonly found in the USA, Europe, and Canada.

In the USA the disease is more likely to be reported in the upper Midwest and the northeastern and mid-Atlantic states (New England, Delaware, Maryland, New Jersey, New York, Pennsylvania, District of Colombia). Over 95% of cases are reported in this region.

Over 60,000 cases of confirmed Lyme disease were reported to CDC in 2022. The true figure is more likely to be closer to 500,000.

Lyme disease is the most reported vector-born disease in Canada. In 2019 a total of 2,634 cases of confirmed and probable cases of Lyme disease were reported in Canada. Most of the cases were reported in Ontario, Quebec, and Nova Scotia.  Lyme disease tends to be a seasonal disease – May to November. Approximately 6% were imported cases from the USA and Europe).

An excellent summary was published by the Public Health Agency of Canada in 2019. This shows an increasing number of recorded cases from 2009.

According to WHO, Lyme disease is low risk for travellers. Despite this, public health authorities are encouraged to provide warnings to communities at risk and travellers.

Those most at risk groups include hikers, campers, and those involved in outdoor work. An outdoor worker in a region of risk is 10 times for likely to be infected than the general population.

Two main factors determine the risk of tick habitation in a particular area: vegetation and climate. This makes it possible for local authorities to warn visitors of the possibility of tick habitation in a particular area. If forewarned, then the visitor can reduce their exposure to ticks.

• Be aware that ticks in the area may carry the disease. Seek information on whether any outbreaks have been reported.
• Take particular care in the season of risk (May to November).
• Wear appropriate clothing to reduce the likelihood of any attachment to the skin. This would include long-sleeved shirts and trousers. Socks should be pulled up over the bottoms of the trousers. Consider impregnating your “hiking clothes” with permethrin. Understand how this should be best applied to the clothing and how many washes before retreatment should be done.
• Wear light coloured clothing. Ticks are easily seen and might refrain from attachment.
• Use known effective repellents on the skin. These include DEET or Picaridin containing products.
• Avoid known tick habitats such as bushy areas with high grass in the high-risk season.
• Stay as much as you can to paths and avoid encountering low bushes.
• Perform tick checks after finishing outside activities and remove any ticks as soon as possible. Check arm pits and groin areas closely. Other areas include the belly button. behind the ears and knees. Clean any affected area with antiseptic. It is suggested that it takes more than 24 to 36 hours for a tick to transmit the disease once attached.
• Use the proper technique to remove any tick. Use tweezers as close to the skin as possible and avoid squeezing the body of the tick. Gloves are recommended to avoid any fluid exposure.  See technique on how to remove a tick.
• Shower in hot water and check for any ticks.
• Inspect your underclothes closely and wash your hiking clothes with hot water as soon as possible. Putting them in a dryer adds extra protection. It is always advisable to travel with extra hiking gear if washing and drying isn’t always available.