A case of measles has been confirmed in Calgary and other people might have been exposed to the contagious disease, Alberta Health Services said in a warning Tuesday.

The potential exposure happened at the Shoppers Drug Mart on Silver Springs Boulevard northwest on April 2 between noon and 2:30 p.m.

Anyone who was at the store during this time and who was born after 1970 — and who has not had the measles or two dose of the vaccine — may be at risk and should watch for symptoms, AHS said.

People who think they fit that criteria should call Health Link at 811.

AHS will also directly contact people believed to have been exposed in other settings.

Dr. David Strong said a confirmed case of measles in Calgary has been traced to an infected passenger on a flight from the United Kingdom to Toronto. (Colin Hall/CBC)

Dr. David Strong, medical officer of health at AHS, said the confirmed case of measles in Calgary has been traced to an infected passenger on a flight from the United Kingdom to Toronto in March.

While the incubation period typically ranges from seven to 21 days, Strong said symptoms in this man's case showed up shortly after 21 days, "which is a little bit unusual."

Strong said the man was infectious but did not know he had measles when he visited the Shoppers Drug Mart.

'Extremely contagious'

Symptoms of measles include:

Fever of 38.3 C or higher, and

Cough, runny nose and/or red eyes, and

A red blotchy rash that appears three to seven days after the fever starts.

"Measles is an extremely contagious disease, spread easily through the air," AHS said. There is no treatment for the disease, but it can be prevented with immunization.

In Alberta, the measles vaccine is offered for free through the province's publicly-funded immunization program.

Children in Alberta usually get their first dose of measles vaccine at 12 months of age and their second between four and six years.

"I think this is a good opportunity for everybody to look to see what their immunization status is, for themselves and for their children and their family, and if they're not sure about that they can contact Health Link or the local community health centre," Strong said.