TORONTO -- Public health officials are investigating after they confirmed a passenger on a flight from Switzerland to Toronto had the measles.

Toronto Public Health says it's confirmed a case of the measles in a passenger travelling on an Air Canada flight from Zurich to Toronto on Tuesday, March 6.

This is the second such incident in less than a month: public health officials confirmed a case of measles in an infant on a Feb. 12 Air Canada flight, also from Zurich to Toronto.

That two cases of measles would surface in less than a month is unusual, says Rita Shahin, associate medical officer of health for Toronto Public Health. But she doesn't think it's cause for concern.

"They're rare cases when we have an imported case of measles," she says. "I think it's just coincidence."

The measles virus is highly contagious, but outbreaks are rare in Canada as most people are immunized. Shahin says only five cases were reported to Toronto Public Health last year, and most of them were travel-related.

Other passengers on the March 6 flight may have been exposed to the measles, but Shahin says it's unlikely the virus spread significantly.

The people who are most susceptible to the infection are infants who have not yet been vaccinated, people with illnesses that weaken their immune systems, and pregnant women.

Symptoms include a high fever, coughing, runny nose, sore eyes, and skin rashes.

Toronto Public Health advises people exhibiting symptoms to avoid work or school, and to contact a health care provider before going in for treatment.