
Lyme disease has settled so deeply into parts of Canada many public-health units now just assume if you get bitten by a tick, you should be treated for Lyme disease.
In Ottawa, where more than two-thirds of the ticks tested in some neighbourhoods carry the bacteria that causes Lyme disease, the public-health unit no longer bothers to test ticks at all.
Vera Etches, the unit’s top doctor, said that in 2016 and 2017 more than one-fifth of black-legged ticks tested in Ottawa came back positive for Lyme.
“That’s a threshold,” she said. “Once you know that more than 20 per cent of the ticks in your area carry Lyme disease bacteria then we don’t need to check in on that. That is what we now call an ’at-risk area.’ ”
That means if a tick is found on a person, and is believed to have been there for more than 24 hours, then the patient should get antibiotics to prevent Lyme infection, even without any testing of the tick. It takes 24 hours before bacteria in the tick’s gut move to its salivary glands and are transferred to a person.
After three days, the preventive treatment won’t work so patients then wait for symptoms or enough time for antibodies to evolve to show up on a test. It can take more than a month before symptoms appear. They’re mostly similar to the effects of influenza, including fever and aches, as well as – usually, but not always – a rash. It typically takes just about as long for the immune system’s antibodies to show up on a lab test.
[…]
See Also: