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CanadaScience & Tech

Habitat Destruction & Climate Change on Lyme Disease in Canada

While the COVID-19 pandemic continues to have a large impact on the health of Canadians, it is important not to forget other diseases that are becoming increasingly problematic within the country. Lyme disease has slowly become a household name in the last few years, largely due to its increasing presence in Canada since 2009—a presence that later made it a nationally notifiable disease. It has the potential to destroy one’s quality of life and is difficult to diagnose. Eventually, the disease has the potential to cause Bell’s Palsy, Lyme carditis, heart palpitations, syncope, intracranial hypertension, alpha-gal syndrome, peripheral neuropathy, Lyme encephalopathy, or Lyme arthritis.  Currently, there is no human vaccine to combat this disease. 

Lyme disease is a bacterial disease that ticks can transmit to humans and other animals. There are many different species of ticks and they all have different likelihoods of transmitting Lyme disease. Very broadly, ticks can be classified as soft or hard. Hard ticks transmit more types of diseases and are primarily responsible for spreading Lyme disease. diagnosis may be made by a healthcare provider after examining one’s health status and travel history, testing the tick specimen (if possible), and a physical examination. Two-tier serological laboratory testing may also be utilized for identification, but it is not always necessary to receive a diagnosis. Symptoms of Lyme disease are very broad and range in severity; however, the most recognizable sign is erythema migrans — commonly referred to as “the bulls-eye rash.” 

Brown Spider on Green Leaf

Close-up of a tick

Lyme disease can be very difficult to diagnose as erythema migrans are not seen in all cases and other early symptoms such as joint pain and dizziness are signs of many other diseases – including influenza. Laboratory testing is limited as it detects antibodies and not the bacteria B. burgdorferi, a causative agent of Lyme disease, itself.  Often antibodies are not detectable in the early stages of the disease which may delay treatment. A large problem with not receiving a proper diagnosis is that patients may not be eligible for sickness benefits, which can further contribute to a reduction in quality of life due to unstable finances.

Not all species of ticks are carriers for Lyme disease so it is important to submit ticks for testing or identification if the specimen can be preserved. Ticks can be safely removed with clean and fine-tipped tweezers. Ticks should be grasped as close to the skin as possible and pulled upwards gently, since squeezing the tick can increase the likelihood of pathogens entering the bloodstream. Twisting the tick is also to be avoided as it can result in parts of its mouth being left embedded in the skin. Ticks should also be removed as soon as possible and individuals should not wait until they naturally detach because the likelihood of Lyme disease being transmitted increases after it has been attached for thirty-six hours. After removing the tick the area should be cleansed. Notably, it is considered dangerous to remove ticks using heat or cover them with nail polish remover or petroleum jelly. Ticks can then be submitted to the appropriate provincial health authorities where they will be sorted and forwarded to the National Microbiology Laboratory. Ticks should be placed in a sealed container/bag and the date of the bite should be recorded. 

Due to Lyme disease only being identified in the 1970s and its first case in Canada being in 2009, many Canadian physicians are not familiar with how the disease progresses and how to diagnose it. Furthermore, the Government of Canada does have a national case definition for Lyme disease which generally follows the recommendations of the Infectious Disease Society of America (IDSA).  However, the International Lyme and Associated Diseases Society (ILADS) is preferred by many alternative practitioners.  The two associations differ in their recommendations regarding the use of antibiotics after a tick bite.  For example, the IDSA supports a single prophylactic dose of antibiotics after a tick bite, whereas the ILADS supports a course of antibiotics if a physician chooses to treat before symptoms appear. The IDSA also tends to place more emphasis on the value of diagnostic tests compared to the ILADS. Depending on which set of recommendations a health practitioner chooses to follow can result in vastly different care received by patients.

The Impact of Habitat Destruction

The bacterium that causes Lyme disease has been around for approximately 60,000 years, according to genome testing by Yale researchers, yet the disease was only named in the 1970s based on the town in Connecticut where it was first identified. How is that possible?  

The answer is in part due to poor environmental planning and resource management. The forest habitats that had existed for thousands of years were destroyed by deforestation and were then developed into human residential and agricultural areas. This resulted in the death of local species. Apex predators such as wolves were hit particularly hard and due to their absence in the food chain, the deer population began to increase but were forced to share space with human settlements. As a result, the ticks that were feeding off of the deer and small rodents managed to hitch a ride into suburban areas. 

Ticks can be reduced in one’s yard by removing leaf litter, keeping grass short, constructing fences to minimize deer entering the yard, and placing gravel/wood chips as a barrier around the lawn. However, strategies to minimize ticks on personal properties are not always eco-friendly. Many environmental organizations such as the David Suzuki Foundation promote leaving leaf litter in place as it is used by worms and insects as insulation during winter months. This can create a moral dilemma for those that want to protect themselves from Lyme disease but also foster an environmentally friendly space in their backyards.

Some have suggested that culling deer populations would reduce the incidence of Lyme disease, however, there is insufficient evidence to prove this. Culling deer could also lead to a trophic cascade and destroy an ecosystem. Others have suggested the widespread use of chemical acaricides which can be toxic and cause further damage to habitats by entering groundwater or killing other beneficial species. Another strategy being considered by some researchers is vaccinating mice that carry B. burgdorferi. This would not impact the number of ticks but it would theoretically decrease the number of infected ticks. At this time animal surveillance remains a crucial tool for tracking trends that may lead to proper environmental resource management strategies.

The Effects of Climate Change

In addition to habitat destruction, climate change has played a large role in the spread of Lyme disease in Canada. The warming annual temperatures mean a longer season for ticks to be active and accelerate their lifecycles. It also allows the parasites to progressively expand their geographic range northward as these regions develop favourable warm conditions for them to thrive. As a result, the tick population can continue to increase and they can spread into new biomes. As global warming continues, it also affects the migratory patterns of birds and allows them to move further north each year. Ticks may use birds as unwitting phoretic hosts and detach themselves wherever the bird lands, thereby providing another way for ticks to be introduced to a new area.

Low Angle Photography of Flock of Flying Birds

Climate change also causes humans to change their behaviours. For example, with longer warm seasons humans can continue outdoor recreational activities which may bring them into contact with ticks for longer periods each year. Clothing choices for warmer weather also tend to be short-sleeved which is not recommended for preventing tick bites.

Climate change also increases health inequities which results in those of lower socioeconomic status being most impacted by vector-borne diseases such as Lyme disease. Reasons for this are housing that is more likely to be near vector breeding sites, reduced access to healthcare, inability to afford necessary antibiotics, reduced access to preventative tools, and fewer means to access educational materials.

What Happens Now?

To tackle Lyme disease the Canadian Lyme Disease Federal Framework needs to be continually revised and made more robust. This will require politicians to legislate stronger environmental protections aimed at slowing climate change and promoting conservation. For politicians to take Lyme disease as a serious issue for their platforms it requires citizens to make their positions known to their Members of Parliament and vote accordingly. The current Canadian Federal Framework was due to the private member Bill C-442 proposed by Elizabeth May of the Green Party. Before this bill, the major political parties of Canada were not invested in Lyme disease as part of their platforms.

Health care professionals will need to continue to educate themselves on Lyme disease and other vector-borne diseases to provide proper care and health teaching. Those that work in forestry and agriculture need to be aware of new illnesses they may be exposed to due to climate change. Multi-disciplinary research panels will need to continue to collaborate on possible solutions to combat Lyme disease without causing further damage to the environment. The public will continue to be required to adapt their habits such as conducting examinations of themselves and pets after being outside and removing ticks as soon as possible if spotted, wearing long-sleeved and light-coloured clothing while outdoors and adding tick removal supplies to their first-aid kits. People should also be prepared to advocate for environmental change, volunteer when possible with organizations such as the Canadian Lyme Disease Foundation to raise awareness, and continually educate themselves on how to protect themselves from vector-borne illnesses such as Lyme disease.

Multiethnic men in sportswear with backpacks resting together and searching for ticks on legs in green lush forest during trek