Toronto Public Health says there is an outbreak of measles in the Greater Toronto Area and officials are warning people to take precautions against the illness.

Health officials have confirmed one more person has been infected with the virus after a rash of cases were reported last week, including one in Halton Region. In total, there are five reported cases.

They say the individual could have inadvertently infected others when he visited a local Wal-Mart, a hospital and a health clinic in the city's east end.

Between April 1 and April 5, the man visited the emergency room and the prenatal assessment department on the third floor of Toronto East General Hospital.

During that time he also visited the Community Health Centre on Queen Street East

He also visited a Wal-Mart store at 1900 Eglinton Avenue East on March 28.

People who visited these locations during the same time period are being asked to call Toronto Public Health at 416-338-7600.

As a preventative measure, health officials are also asking everyone who was born before 1970 and who have not been vaccinated against the measles to contact their doctor.

The city will also hold two vaccination clinics to accommodate people who need to be vaccinated against the illness. They will run Tuesday and Wednesday from 3 p.m. to 7 p.m. at the East York Civic Centre, across the street from the hospital.

Dr. Neil Rau, an expert in infectious diseases, told CTV Toronto that it is unusual to have such a high number of cases of the measles.

"This is certainly more cases than one would usually see, so in a sense that's what would be called an outbreak or at the minimum, a cluster," he said.

Measles contagious

The danger to the overall public is low, health officials say.

Most people have been vaccinated against the illness and for those who have already had the measles are now immune to it.

The greatest risk is to those born in developing countries where the vaccination rates are low. In Toronto, a city with a high number of newcomers, the risk is greater.

"I think given that these cases spread so easily to those who don't have immunity or protection from the disease, one can expect to seen new chains of a few cases here and there," Rau said.

Measles can be spread between two people talking or even just standing in close proximity to an infected person.

Symptoms include fever, a rash and itchy eyes.

Children under the age of five, adults over 20 and pregnant women are at the greatest risk.

With a report from CTV Toronto's Chris Eby