New data published on Friday by a team of researchers at the University of Ottawa shows that tick populations in the national capital are more widespread than initially thought and it’s likely the city will see an increase in risk areas for Lyme disease in the coming years.
A three-year study launched last year, spearheaded by Dr. Manisha Kulkarni of the university’s school of epidemiology and public health, is monitoring 23 areas across the city of Ottawa for the existence and density of black-legged ticks, which are carriers of the bacteria that causes Lyme disease.
Data that Kulkarni’s team collected in 2017 found black-legged ticks in 16 – or 70 per cent – of those 23 sites, mostly located in the Greenbelt. Of the 220 adult and juvenile ticks they gathered that year and tested back at the lab, nearly one in three – or 30 per cent – were infected with the Lyme disease bacteria.
The results are significant, not only because of what the numbers show, but because this is the first time researchers and public health officials in Ottawa have more concrete data to reference.
“We’re hoping by doing this year after year, we’re going to be able to collect a really strong dataset to do some really solid research.”
Until now, Ottawa Public Health relied on health care providers and the public to submit ticks for testing and to report cases of Lyme disease in order to get an idea of where tick populations were located in the city.
Kulkarni said her team used what little data was available to determine which sites to measure for ticks. The 23 sites they ultimately chose included nine municipal parks, seven conservation areas and forests, six recreational trails and the Rideau River Provincial Park.
The tick-gathering process involves going into the woods, dragging flannel sheets across grass, plants and bushes and collecting any ticks that attach to the sheets every 25 metres. Rushing the flannel over vegetation simulates the movement of a host animal – like a deer – passing by, which prompts the ticks to grab on, Kulkarni explained.
After collecting ticks in those 23 areas during the spring and fall of 2017 – peak times for tick activity – the researchers found there were “significantly higher” tick densities in recreational trails and conservation areas, for example, than in municipal parks.
Kulkarni cited Carp Hills, Stony Swamp and the South March Highlands, all located in the city’s west end, as examples of areas they expected to find high densities of the critters, and did.
Some surprises, though, included areas east and south of the downtown core and sites along the Ottawa River where they found lower-density populations of ticks.
Kulkarni said this new data and other environmental and ecological factors like climate change suggest it’s likely ticks will continue to migrate to more parts of Ottawa, leading to an increase in Lyme disease-risk areas in the city.
On the flip side, the research team found no ticks in urban parks. Kulkarni said those parks typically don’t have wooded areas big enough to support tick reproduction.
The results from the data Kulkarni’s team collected last year were published today in the Canada Communicable Disease Report. The researchers are now in their second year of data collection. They plan to analyze the fresh data in the winter and publish the results next summer.
Kulkarni said the plan is to share the data with Ottawa Public Health and the National Capital Commission, in hopes the two agencies will use it to inform their public health messaging and awareness campaigns.
Protecting yourself against tick bites
The number of confirmed and probable cases of Lyme disease reported to Ottawa Public Health has spiked significantly since 2014. Four years ago, the public health agency noted 22 cases of the disease. That increased to 73 in 2015 and then 186 in 2017.
And Ottawa’s not alone – it’s been widely reported that the number of cases in Lyme disease is up across the country.
WATCH: Lyme disease on the rise in Canada
Common symptoms of the disease include fatigue and joint pain, but also facial paralysis and heart conditions, in some cases.
While an infection can be serious, Kulkarni said the news that tick populations are popping up in more areas in Ottawa should not scare residents from spending time in nature.
“It’s healthy to go out and be in the woods … but at the same time, have the knowledge that there can be ticks present in many wooded areas around Ottawa,” Kulkarni said. “So be aware, take precautions to avoid tick bites and do those tick checks when you come back to make sure that anything that’s attached is being promptly removed so you can go and seek medical attention.”
Some common precautions Kulkarni suggested include:
- Wearing long-sleeved shirts, pants and boots when out in the woods.
- Using insect repellant with DEET or icaridin on your legs.
- Sticking to trails and pathways in wooded areas.