Albertans are being told to be on the alert for ticks, after random testing turned up the type of tick that can cause Lyme disease.

Alberta's chief medical officer of health, Dr. Andre Corriveau, says the discovery came from a routine surveillance program in which veterinarians are asked to pick ticks off of pets and then submit them to labs for testing.

Tests conducted this week on ticks found in Calgary, High River and areas near Edmonton showed three ticks tested positive for Borrelia burgdorferi, the bacterium that causes Lyme disease.

The bacterium was first found in Alberta in ticks in 2007. Since then, the province has run a tick surveillance program asking vets to watch for the disease. But the bacteria and the species of tick that carries them have been found only rarely since.

With this week's news that three ticks with the bacteria have already been identified, Alberta health officials say they are trying to get a better understanding of the scope of the problem. In the meantime, Corriveau says he wants Albertans to be aware of the risk, especially as camping season approaches.

"Lyme disease can be a serious condition if it's not detected early and left untreated," Corriveau said in a statement Thursday.

He urged the public to guard against tick bites by covering up exposed skin while walking through brush or tall grass, and wearing bug repellent when possible.

"Your best defense against Lyme disease is prevention."

Lyme disease is a complex and still little-understood illness. If it's caught early, it can be eradicated with a long course of antibiotics. But if left undiagnosed, the illness can establish itself and cause everything from painful joints to chronic flu-like symptoms and debilitating neurological problems.

It can be hard to diagnose because its symptoms are so varied and non-specific. What's more, the blood test used in Canada for Lyme disease is notoriously unreliable, and many people who test negative often have to undergo numerous tests before the illness can be ruled out.

For those reasons, it's unclear how big a problem Lyme disease is in Canada.

Corriveau says 20 cases were recorded in Alberta between 1989 and 2009, but it remains unclear where those infections were picked up.

"The cases we've had in humans in the past in Alberta tended to be people that travelled elsewhere, so they weren't believed to have acquired it in the province," Corriveau said.

So far, only adult Lyme disease-carrying ticks have been found, perhaps brought from migratory birds. With no immature ticks yet found, that suggests the insect is not yet established in Alberta, said Dr. Gerald Hauer, Alberta's chief veterinarian.

Health officials note that Lyme disease can affect pets as well as people. They suggest that if you find a tick on your pet, you should contact your local veterinarian to remove it, so the tick can be identified and collected for testing. Veterinarians can treat the infection in pets.

In humans, ticks will often embed themselves in the skin and need to be removed with tweezers. Tick bites usually look like a circular, red rash that appears between three and 30 days after the bite.

Albertans who suspect they have Lyme disease should contact HealthLink Alberta, at 1-866-408-5465.