Two dozen Canadians were wrongly told they didn't have Lyme disease when they in fact have the illness, CBC News has learned.

Lyme disease is caused by a bite from an infected tick. Without antibiotic treatment, it can make people feel fatigue, chills, fever, headache, muscle and joint pain and memory or neurologic problems that can linger for months or years.

Canada's National Microbiology Laboratory in Winnipeg discovered a mistake in 24 test results last month. Of these, 16 people were treated, two never fell sick enough to seek treatment, one is going to get treatment, and there's no information on the other five.

"There are 24 individuals who we reported out falsely, negative test results," Dr. Frank Plummer, scientific director of the National Microbiology Laboratory said Thursday from Mexico City. "They should have been reported as positive."

The people are in Manitoba, Quebec and Nova Scotia, the Public Health Agency of Canada said.

Lyme disease has an acute phase that can become chronic. If so, significant ill health such as arthritis and neurologic problems can occur.

"It remains treatable, once the individual is properly diagnosed they can receive treatment and should get better," Plummer said.

Provincial health officials are working to inform those affected through their family doctors.

Plummer said doctors take three factors into account when advising treatment for Lyme disease:

  • The clinical picture, such as a tell-tale red rash that often appears where the tick bit.
  • Exposure to the black-legged tick that transmits the disease.
  • Laboratory testing to confirm.

The mistake happened as the lab evaluated a new test kit that uses an automated reader. The kit has the potential to be give more reliable results, Plummer said.

The lab is still using the automated test, but is working with the kit manufacturer to find out if staff training or software issues with the scanner are behind the problem, he added. 

The Public Health Agency of Canada is also calling for an independent review of the test and testing process.