Risk on the rise: New project maps out Lyme disease risks across Ottawa area

Posted on Wednesday, August 2, 2017

Author: IM

Dr. Manisha Kulkarni pulls out a clear plastic container from a brown paper bag in her laboratory. Inside are a few black specks, dots the size of sesame seeds. They are blacklegged ticks captured by Ottawa-area residents, sometimes after the latter have been bitten.

The blacklegged tick carries the Borrelia burgdorferi bacteria, which can cause Lyme disease and lead to a wide range of symptoms, including headaches, joint pain, stiffness and flu-like symptoms, as well as a characteristic “bull’s eye” rash. The chance of infection increases when a tick remains attached for 24 hours or more. If a person becomes infected, symptoms typically begin within 30 days after the bite.

Remove ticks promptly with tweezers grabbing as closely to the tick’s mouth parts as possible. Image shows tweezers grabbing a tick attached to skin.

With tick populations expanding northward, Lyme disease risk in the Ottawa area is on the rise. Kulkarni, a medical entomologist at the University of Ottawa’s School of Epidemiology and Public Health, is collaborating with Ottawa Public Health to develop new approaches to monitor and understand Lyme disease emergence in the area. Her team at uOttawa is studying the spread of ticks and Lyme disease to identify who is at risk. Her findings may help develop strategies to mitigate chances of people being exposed to the disease.

The team’s approach is two-fold: first, create an ecological model of where ticks can be found in the area and the proportion that test positive for Lyme disease. This will help the team map out gradations of risk of Lyme disease. Then turning its attention to the human impact of the research, the team superimposes its ecological model with satellite images and data on areas where people diagnosed with Lyme disease live and were exposed, information on demographic groups, and observations on how people use the surrounding environment. With this data, the team can get a good idea of the likelihood and risk factors for people getting exposed to Lyme disease.

“With urbanization, residential neighbourhoods are spreading into what used to be wooded areas where ticks are found. This means that in many parts of the city, people can pick up ticks while walking through tall grasses, bush, or wooded areas in their neighbourhoods, or even in their own backyards,” says Kulkarni.

Using innovative multidisciplinary methods, the team combines environmental and epidemiological data at a local scale, helping monitor risks over the longer term. “We want to reinforce the message that the risk of Lyme disease is expanding in Ottawa,” says Kulkarni. “Ticks are now part of our environment, and people need to be informed of risks and ways to protect themselves.”

Kulkarni notes that city-wide, approximately one out of five ticks tests positive for Lyme disease, with areas where rates are higher or lower. Human cases of Lyme disease have risen over the last several year and Kulkarni expects this trend will continue in the years to come.

“It is important for residents to be extra cautious during the summer, as ticks, now in the nymph stage of their development, are smaller and more difficult to see,” says Kulkarni, adding an immature tick can be the size of a poppy seed.

 a woman applies insect repellent, checks body for ticks, a man bathes to remove all ticks not attached to skin, clothes in a dryer.

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