People who bought a puppy at a Toronto flea market last weekend should go see their doctor, even if their dog is not exhibiting symptoms of rabies, urged a Toronto Public Health Official on Thursday.

"This is very serious," Dr. Rosana Pellizzari, with Toronto Public Health, told CTV Toronto. "Rabies should be treated as a fatal illness -- no ifs and or buts."

Officials believe at least 60 people came into contact with a rabid dog on Jan. 3. The infected puppy was being held with 10 to 12 other dogs.

They have all been sold and health officials believe they have all been infected with rabies. At least three different breeds are involved.

The infected puppy and one other dog in the group have died, Susan Sperling, spokesperson with Toronto Public Health confirmed to CTV.ca.

Since the alert was issued Wednesday, officials have received about 200 calls from concerned people.

"Any resident who came in contact will be assessed and referred for treatment if required," Pellizzari said.

So far, six of the dogs have been located, including the two that died. They are being held in quarantine for the next six months.

Officials are looking for three border collies, one yorkie cross, a maltese and an unknown breed.

The flea market booth had a "Pets R Us" sign posted on it.

Rabies can lie dormant

Rabies can lie dormant in an infected animal for up to six months. However, people can become infected by their pets even before the animal begins to show symptoms of the illness.

Humans can not pass rabies to other humans.

Flu-like symptoms are often the first signs of rabies in humans but Sperling stressed the pet owners need to get checked out before they begin to feel sick.

If treated early enough, the vaccine is "extremely effective" against rabies, she said. However, rabies is fatal if left untreated.

Concerns arose after a sick dog bit a worker at the Toronto Humane Society about one week ago. The border collie cross died later that night, and test results showed it had rabies.

The puppy was brought in to the THS once the owners realized the puppy they bought at the flea market was sick.

The worker who was bitten by the dog has received rabies shots and is doing fine, but health officials say others may still be at risk.

So far there are no known human cases but health officials would like to hear from anyone who may have come into contact with the puppy -- or any puppy sold at booth number 1513 at Dr. Flea's Market, at Highway 27 and Albion Rd., on Jan. 13.

Here are some regional numbers to call if you believe you came in contact with the puppies:

• Toronto Public Health at 416-338-7600
• York Region Public Health at 1-800-361-5653
• Peel Region Public Health at 905-799-7700

With a report from CTV Toronto's Alicia Kay-Markson