The measles case announced by public health officials over the weekend is linked to a previous case in Hamilton from earlier this month, CBC News has learned.

The most recent case stems from a confirmed measles infection that came from a man who travelled to the Philippines on March 14, says Hamidah Meghani, associate medical officer of health for the city. That means the virus has spread, and is officially an outbreak. It has now infected two people in Hamilton and another in Halton region.

“This is a secondary case,” said Hamidah Meghani, associate medical officer of health for the city. “Given the number of exposure settings, we are concerned.”

“We’re also concerned because not everyone in the community has been vaccinated.”

People who visited the following locations at certain times may be at risk:

Saturday March 22, 2014:

  • Skyzone Indoor Trampoline Park, 3636 Hawkestone Rd., Mississauga, 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.

Sunday March 23, 2014:

  • Mill Street & 5 American House, 324 Dundas St. E, Waterdown, 1 a.m. to 2 a.m.
  • Milestones Restaurant, 1200 Brant St., Burlington, 7 p.m. to midnight

Monday March 24, 2014:

  • Canada Post office, 17 Main St. N, Waterdown, 5 p.m. to 6 p.m.
  • Boston Pizza, 4 Horseshoe Cr., Waterdown, 5:15 p.m. to 10:30 p.m.

Wednesday March 26, 2014:

  • Lakeside Variety store, 721 Beach Blvd., Hamilton, 9:30 a.m. to 11:30 a.m.
  • Walmart, 90 Dundas St. E. Waterdown, 2 p.m. to 4:45 p.m.

The city is in the process of creating a hotline for people to call if they’re concerned that they’ve been exposed to the virus. The hotline number is (905) 546-2424 ext. 7970. It’s especially important for people who think they may have been exposed on Wednesday at Walmart or Lakeside Variety to contact public health, as they could still be given immunoglobulin to try and prevent infection.

More information on the measles will shortly be posted to the city’s website, Meghani told CBC Hamilton. Anyone from Hamilton who isn’t sure if they’ve had both of their measles shots can call the hotline to access that information, too.

“It’s a highly contagious viral infection,” she said. Measles is spread through the air, and people are usually contagious before they have symptoms. “It can lead to a lot of exposures because they’re not aware of their illness,” Meghani said.

Easily spread to people without immunity

A bad cough, runny nose, fever, sensitivity to light and red-watery eyes are symptoms commonly associated with the virus. Spots with a white centre can also appear inside the mouth.  A red rash may also appear and last for four to seven days.

About four days after infection, a rash starts at the face and moves down the body. White spots may appear inside the mouth. People with measles are contagious until four days after the rash first appears.

The virus spreads easily to people who aren’t immune. Infants under a year of age, pregnant women and people with weakened immune systems can get particularly ill.

Complications can include ear infections, pneumonia, croup and brain inflammation.

Meghani says the best way to protect yourself from the virus is to be vaccinated. “The best choice is to vaccinate yourself,” she said.

B.C. measles outbreak caused by low immunization rates

But not everyone chooses to be vaccinated. There were 228 cases of measles confirmed in parts of British Columbia's Fraser Valley earlier this month, a region east of Vancouver where immunization rates are low in some school and religious groups.

“The people who don’t vaccinate need to think very carefully about the outcomes of their choices,” said Lisa Schwartz, the Arnold L. Johnson chair in health care ethics at McMaster University.

There have been more measles cases than normal in Canada this year, according to the Public Health Agency of Canada.

Cases have been reported in British Columbia, Alberta, Saskatchewan, Manitoba and Ontario. The virus is relatively rare in Canada thanks to high immunization rates. "However, Canada will continue to see measles cases related to travel to countries where measles is endemic or there are large outbreaks, such as the Philippines and the Netherlands," the public health website reads.

Schwartz says there is a lot of misinformation out there about the perceived safety of vaccines. A medical journal in Britain ended up retracting a controversial study it published in 1998 that linked the use of a vaccine in children to autism. Actress Jenny McCarthy has also long suggested a link between vaccines and autism. “But the data that led people to have those kinds of fears doesn’t hold up to scientific scrutiny,” Schwartz said.

“Obviously celebrities will be taking stands on things – but we should be looking to real authorities,” Schwartz said.