Health officials are warning the public after a Hamilton, Ont. man who has tested positive for measles may have exposed people in three cities to the virus.

Hamilton Public Health Services said the man visited a number of public places in Hamilton, Burlington and Mississauga between March 22 and March 26.

Individuals who visited the following places may be at risk:

March 22

Skyzone Indoor Trampoline Park, 3636 Hawkestone Rd., Mississauga, Ont., 12:30 p.m. to 4:30 p.m.

The Queen’s Head pub, 400 Brant St., Burlington, 10 p.m. to 2 a.m.

March 23

Mill Street & 5 American House, 324 Dundas St. East, Waterdown, Ont., 1 a.m. to 2 a.m.

Milestone Restaurant, 1200 Brant St., Burlingon, 7 p.m. to midnight

March 24

Canada Post office, 17 Main St. North, Waterdown, Ont. 5 p.m. to 6 p.m.

Boston Pizza, 4 Horseshoe Cres., Waterdown, Ont., 5:15 p.m. to 10:30 p.m.

March 26

Lakeside Variety store, 721 Beach Blvd., Hamilton, Ont., 9:30 a.m. to 11:30 a.m.

Walmart, 90 Dundas St. East, Waterdown, Ont., 2 p.m. to 4:45 p.m.

Children who are under one year of age, pregnant women, and people with weakened immune systems can become “very ill with measles,” the Hamilton Public Services said in a news release on Sunday.

The measles virus is highly contagious, and can spread through the air when an infected person coughs or sneezes.

"To avoid spreading illness to others it’s important that ill individuals stay home," Dr. Hamidah Meghani, Hamilton’s associate medical officer of health, said in a statement.

Symptoms include:

Fever

Cold-like symptoms such as a cough or runny nose

Red and inflamed eyes

Small spots with a white centre that appear on the inside of the mouth

Rash starting lasting four to seven days

About one in 3,000 cases is fatal.

Individuals who were at the above mentioned locations during the specified times, and have not been immunized or have not had measles in the past, are asked to contact: