As the Calgary Stampede kicks off, health experts are warning about the risk of measles exposure and are urging parents with babies and unimmunized children — along with other vulnerable Albertans — to sit this one out.
The Stampede attracts travellers from all over Alberta and around the world. This year organizers expect more than 1.3 million people will attend.
This annual event comes at a time when the province is battling its worst measles outbreaks in nearly half a century. As of noon Thursday, 1,179 cases had been reported since the outbreaks began in March.
“That’s a lot of people over 10 days in a concentrated area and that’s where the risk factor is,” said Dr. Sam Wong, president of the section of pediatrics with the Alberta Medical Association.
“If I had an infant child I would be avoiding Stampede and any large gathering like that because I would want to protect my child as much as possible.”
Measles can lead to a number of severe complications including pneumonia, brain inflammation, premature delivery and even death.
Young children, pregnant people and people who are immunocompromised are at higher risk of severe complications.
And until babies are old enough to be vaccinated, they’re extremely vulnerable.
“I grew up in Calgary. I’m a big fan of the Stampede,” said Wong. “But there are risks associated with it this year.”
A premature baby who was born infected with measles recently died in Ontario. A young child in that province also died due to measles last year.
Alberta’s routine childhood immunization schedule recommends babies get their first measles vaccine dose at 12 months old and their second shot at 18 months.
Due to the outbreaks the province is offering an early and extra dose to babies as young as six months old living in the south, central and north zones.
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The University of Calgary’s Craig Jenne is also worried about adults and children who are unvaccinated or have just one dose. The vast majority of Alberta’s measles cases have been among the unimmunized.
“We do know, simply statistically, that measles will be present on the Stampede grounds,” said Jenne, a professor in the department of microbiology, immunology and infectious diseases at the university.
People travelling to Calgary from parts of the province with outbreaks, including the hardest hit south, north and central zones, could bring the virus with them, he said.
“We are still seeing daily exposures in multiple health zones in the province. So measles is still freely transmitting.”
Measles is a highly contagious airborne illness and it can spread both indoors and outdoors, Jenne said.
“When we think of the crowds at Stampede, people are very close together and the measles virus is very infectious. So we do know that this is the kind of environment where… a virus like measles can very easily spread.”
The measles virus can hang in the air for up to two hours after a person has left a space. And people can spread the disease before they have symptoms.
“If somebody with measles goes into an indoor space and walks into a building or pavilion and then leaves, the virus could be in the air for hours after that person was in there, so potentially exposing people who come in even much later in the day, to the virus,” said Jenne.
“If you are unvaccinated and in a risk group these large gatherings may pose an exposure risk which we really need people to avoid.”
Other gatherings, such as Edmonton’s K-Days, scheduled for later in July, are also a concern because they too draw large crowds, he said.
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Dr. Karina Top, a pediatric infectious disease physician at the Stollery Children’s Hospital in Edmonton, is also urging high risk Albertans and people with vulnerable infants to stay away from large gatherings.
“I’m quite worried about the potential for spread of measles at these types of events,” she said.
“If the risk wasn’t high, I wouldn’t be suggesting people stay home. But it is. And I really don’t want anyone to get severely ill from going out to enjoy Stampede.”
She’s also concerned Stampede could trigger more outbreaks in the province, including in Calgary, which has so far experienced low case numbers.
Since the outbreaks began in March, 24 measles cases have been reported in the Calgary zone and there have been 10 in the Edmonton zone.
The province said it continues to encourage all Albertans to check their immunization records and ensure they and their children are up to date.
“We acknowledge that large events such as the Calgary Stampede could potentially increase the risk of exposure to respiratory viruses, including measles, and we will continue to monitor the situation closely,” an official with Primary and Preventative Health Services said in a statement emailed to CBC News.
“We continue to recommend that anyone attending large gatherings — such as the Stampede — ensure their immunizations are up to date, practice good hand hygiene, and stay home if feeling unwell.”
Being aware of the risks is key, according to the health official.
“Individuals who cannot be immunized and are at higher risk of severe measles complications — such as pregnant people, children under the age of five, and those who are immunocompromised — should be aware that large gatherings may increase the risk of exposure,” the statement said.
“It’s important that these individuals carefully consider the potential risks and make informed decisions about attending based on their personal circumstances and comfort with the level of risk.”
The province’s measles awareness campaign, “Don’t Get Measles, Get Immunized,” has been extended into early August, the spokesperson said, adding case counts and exposure notifications are updated regularly on Alberta’s measles webpage .
In addition, the province pointed to a Measles and Community Events guidance document for organizations, staff, volunteers and attendees.
CBC News asked if signs would be posted on Stampede grounds warning about Alberta’s measles outbreaks.
Stampede officials did not answer that question, and the province said no additional advice had been provided on posting signs.
“We encourage guests to follow the guidance of public health authorities,” a spokesperson for the Calgary Stampede said in an email. “If you are feeling unwell, we kindly ask that you stay home.”
For her part, Top is calling for strong messaging about the risks.
“And to provide guidance for people on how to protect themselves because I think there’s real potential for this to take off like wildfire,” she said.
Meanwhile, Jenne will be watching for cases during Stampede and in the weeks following. Reining in the virus will prove extremely difficult for public health teams, he warns, once exposures occur.
“Where there could be more than 100,000 people a day on the grounds, contact tracing becomes impossible,” he said.
“And trying to get ahead and put exposure alerts out becomes, again, impossible in scenarios such as these large gatherings.”
