Case challenge: Lyme disease
Module: health threats
Chapter: vector-borne disease
Questions to think about before scrolling:
What is Lyme disease?
Has the incidence of Lyme disease changed?
What can be done to reduce your risk of tick bites when outdoors?
The Patient:
Liam Dias, a 32-year-old male, presents to your family practice in Kitimat, BC. He was in Manitoba, visiting family and doing some hiking in Turtle Mountain Provincial Park. He arrived back home yesterday and discovered a tick on his left leg after a day hike through the Manitoba trails. He is concerned about Lyme disease.
What is Lyme disease?
This tick-borne disease is the most common VBD affecting humans in the temperate Northern Hemisphere. [1] Ixodes ticks (commonly known as black-legged or deer ticks), can transmit bacterium borrelia burgdoferi to humans via a bite, subsequently potentially causing Lyme disease. Clinically, it can present with an erythema migrans rash, lymphadenopathy, and fever. If left untreated, it can result in further neurological, cardiac, or joint involvement. [2]
The Context:
Liam is afebrile, with unremarkable vital signs. You examine his left leg and see a confluent erythematous rash surrounding a bite on his left leg. [3] The patient says he noticed the tick in the evening after his hike (2 days ago), and removed it once noticing it, the evening after his hike. He removed the tick with tweezers and has brought it into your office today in a sealed container with a damp cotton ball. [4] He states that the tick was not engorged.
You commend him for promptly noticing and removing the tick, as the faster the tick is removed, the transmission of Lyme disease is less likely. [5]
“I feel like I’ve been hearing more about Lyme disease lately, is there any reason for that?”
Has the incidence of Lyme disease changed?
Great question! The incidence of Lyme disease in Canada is increasing, and it is believed to be related to changes in climate that facilitate the geographical spread of Lyme disease. [6] The first infected tick was found in Southern Ontario in the 1990’s, and since then this disease has progressed northward, with cases now found in Ontario, Quebec, New Brunswick, Nova Scotia, Manitoba and BC. [7] The incidence of Lyme disease has risen by over 3 fold from 2009 to 2016 in Canada. As of 2016, 88% of cases being reported were in Quebec, Ontario and Nova Scotia, but simulations accounting for future climate change predict further spread of this disease, and it may soon be of increasing relevance in BC. [8]
What is the proper technique to remove a tick?
BC CDC recommends using tweezers, with a slow and gentle pull, without twisting, or crushing the body. This ensures that the tick is removed with the mouth part still attached. If the tick is buried deep in your skin, you should see a doctor to help with removal. Physicians can submit ticks to BCCDC Public Health Laboratory for testing, so save the tick with a damp cotton ball in a sealed container for possible testing. [4]
What can be done to reduce your risk of tick bites when outdoors?
Although the risk of being bitten by a tick carrying Lyme disease is quite low, the disease can be very serious making it important to be aware of ways to reduce your risk of being bitten.
Walk in cleared trails when hiking in tall grassy, or forested areas
Tuck your pants into your boots or socks, and wear light coloured clothing in order to easily see ticks
Use DEET containing insect repellent on areas of uncovered skin
When leaving an area where ticks may be found, take a bath or shower to remove loosely attached ticks, and put clothes in a hot dryer for 10 minutes to kill any attached ticks
Inspect your entire body for ticks – including your scalp, and folds of skin such as under the arms, and behind your knees
Check children and pets for ticks [9, 10]
The Outcome:
You are called away to see another patient, and your preceptor finishes up the consult. After testing, Liam is relieved to hear that the tick was negative for borrelia burgdoferi. He continues hiking, but is aware of ticks and uses preventative measures to reduce his risk of getting bitten again.
References
[1] Caminade, C., Mcintyre, K. M., & Jones, A. E. (2018). Impact of recent and future climate change on vector-borne diseases. Annals of the New York Academy of Sciences, 1436(1), 157–173. doi: 10.1111/nyas.13950
[2] Halperin, J. J. (2017). Nervous System Lyme Disease. Oxford Medicine Online. doi: 10.1093/med/9780199937837.003.0159
[3] “Signs and Symptoms of Untreated Lyme Disease.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 15 Jan. 2021, www.cdc.gov/lyme/signs_symptoms/index.html.
[4] Canada, P., 2021. Removing and submitting ticks for testing - Canada.ca. [online] Canada.ca. Available at: <https://www.canada.ca/en/public-health/services/diseases/lyme-disease/removing-submitting-ticks-testing.html> [Accessed 4 May 2021].
[5] Transmission. (2020, January 29). Retrieved May 04, 2021, from https://www.cdc.gov/lyme/transmission/index.html#:~:text=In%20most%20cases%2C%20the%20tick,of%20immature%20ticks%20called%20nymphs.
[6] Mathieu, K., & Karmali, M. (2016). Vector-borne diseases, climate change and healthy urban living: Next steps. Canada Communicable Disease Report, 42(10), 220–221. doi: 10.14745/ccdr.v42i10a13
[7] Gasmi, S., Ogden, N., Leighton, P., Adam-Poupart, A., Milord, F., Lindsay, R., Barkati, S., & Thivierge, K. (2017). Practices of Lyme disease diagnosis and treatment by general practitioners in Quebec, 2008–2015. BMC Family Practice, 18(65). doi: 10.1186/s12875-017-0636-y
[8] Government of Canada. 2018. Surveillance of Lyme disease. Vol. 2018. https://www.canada.ca/en/public-health/services/diseases/lyme-disease/surveillance-lyme disease.html. Accessed July 30, 2018.
[9] Canada, P. (2015, June 18). Government of Canada. Retrieved May 04, 2021, from https://www.canada.ca/en/public-health/services/diseases/lyme-disease/prevention-lyme-disease.html
[10] Lyme disease. (n.d.). Retrieved May 04, 2021, from http://www.bccdc.ca/health-info/diseases-conditions/lyme-disease-borrelia-burgdorferi-infection