The CDC tells U.S. health care workers to be on alert for measles. Should Canadians be worried?

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Health care workers in the United States have been notified by the Centers for Disease Control and Prevention (CDC) to be on alert for measles cases.

According to a Jan. 25 newsletter from the CDC, between Dec. 1, 2023 and Jan. 23, 2024, there have been 23 cases of measles reported. Seven cases were imported from international travellers and two outbreaks with more than five infections each.

"Most of these cases were among children and adolescents who had not received a measles-containing vaccine (MMR or MMRV), even if age eligible," the newsletter said.

The CDC urged health care workers to be on the lookout for measles symptoms including febrile rash illness and patients who have recently traveled abroad to countries with an ongoing measles outbreak.

"Measles cases often originate from unvaccinated or undervaccinated U.S. residents who travel internationally and then transmit the disease to people who are not vaccinated against measles," the CDC said. "The increased number of measles importations seen in recent weeks is reflective of a rise in global measles cases and a growing global threat from the disease."

The CDC's newsletter comes just months after the World Health Organization (WHO) reported a global increase in measles cases and fatalities.

With the latest outbreak just south of the border, should Canadians be worried about measles?

What is measles?

According to the CDC, measles is a "highly contagious" airborne viral infection transmitted by talking, sneezing or coughing with symptoms that may include:

• a very high fever

• a rash that looks like small red dots that typically develops three to seven days after infection

• cough

• red watery eyes

• small white bumps that appear inside the mouth

• fatigue

• runny nose

• sore throat

• muscle pain

• sensitivity to light

There is no treatment for measles. Vaccination is the best way to protect yourself from contracting the virus.

Complications from measles

It takes most people two to three weeks to recover from measles. However, there are a host of complications that range in severity that can occur.

Common symptoms of measles can include ear infection, pneumonia and diarrhea. More severe complications of measles can include developing encephalitis (inflammation of the brain), which can have long term effects such as vision and hearing loss and speech and memory issues.

Measles can also cause respiratory failure and death.

Dr. Isaac Bogoch, an infectious disease specialist with the University of Toronto, said there are common misconceptions about measles that prevent people from understanding how "dangerous" the infection can be.

"Measles has a knack to inhibit the immune system and wipe out prior immunity to other vaccines that you might have had," Bogoch told Yahoo Canada. "That's why it's such a terrible infection. People might have some of their regular childhood vaccines. But measles can actually cause an immunosuppression of sorts and make people more prone to infections that they might have even been vaccinated to in the past. So it's a really nasty infection."

Should Canadians be worried about measles?

Health Canada reported there were a total of 12 measles cases in 2023. Bogoch said the high immunization rate amongst Canadians helps protect Canada from measles outbreaks, and many of the cases that do occur are imported from other countries.

"It's the most contagious infection on the planet. It's so transmissible," he said. "It will find a way
to unvaccinated individuals."

In Canada, the current recommendation is a two dose MMR vaccine. The first dose is administered when babies are between 12 to 15 months old with a second dose given at approximately 18 months of age, or before children enter daycare or school.

Bogoch said people born before the mid-'90s may need to check their immunization records. Although the two dose vaccine is now the standard in Canada, the second dose was introduced in 1996. While there were nation-wide campaigns to administer a second dose, many Canadians may not know that they're not fully vaccinated against measles.

Checking your vaccination card or asking your health care professional can help ensure you're up to date on your vaccines. If you're not sure, Bogoch said a simple blood test can help determine if you're immune or not.

"There is no reason to have a case of measles transmitted within the country," Bogoch said. "There's no reason to have this. We can't control what happens outside of Canada, so we'll see imported cases from time to time. But there is no reason we should have cases transmitted within the country."

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