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Canada needs to act fast to get the monkeypox outbreak under control by scaling up testing, identifying cases quickly and solving key unanswered questions about the origin and ongoing spread of the virus before it takes root here and puts our most vulnerable at risk, public health experts say.
There have been 112 confirmed cases in Canada to date — one in British Columbia, four in Alberta, nine in Ontario and 98 in Quebec — but officials said Friday they are expecting that number to rise in the days and weeks ahead as more results come in.
“Our primary goal is to contain the outbreak,” Canada’s chief public health officer, Dr. Theresa Tam, said during a press conference on Friday.
“This means rapidly stopping chains of transmission to prevent the establishment of monkeypox in Canada and protect public health and health care in Canada.”
Tam said all of the patients are males between the ages of 20 and 63, and the majority of them had sexual contact with other men, but she stressed that the infection can spread to anyone who is exposed through close contact with an infected person or contaminated objects.
“We’ve got to try and get the current outbreak of monkeypox contained,” said Jason Kindrachuk, assistant professor of viral pathogenesis at the University of Manitoba in Winnipeg and Canada Research Chair of emerging viruses who has studied monkeypox.
“Especially when we’re still dealing with a pandemic. Viruses and infectious diseases don’t just stop when a new one emerges; they become cumulative.”
Limited testing may hide true spread
But due to limited surveillance in the general community and the time it takes to diagnose and send samples to the National Microbiology Laboratory in Winnipeg for confirmation, Canada is likely weeks behind in identifying the true scope of monkeypox spread.
The World Health Organization (WHO) said this week that there are more than 1,000 confirmed monkeypox cases in 29 non-endemic countries around the world, but some researchers estimate the true number is more than 1,500 and growing rapidly.
“The sudden and unexpected appearance of monkeypox in several non-endemic countries suggests that there might have been undetected transmission for some time. How long? We don’t know,” WHO director general Tedros Adhanom Ghebreyesus said this week. “The risk of monkeypox becoming established in non-endemic countries is real.”
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Tedros said that while health officials are particularly concerned about the threat monkeypox poses to vulnerable groups such as children and pregnant women, countries such as Canada can step up before the virus becomes established on our soil.
“That scenario can be prevented,” he said. “WHO urges affected countries to make every effort to identify all cases and contacts to control this outbreak and prevent onward spread.”
Dr. Zain Chagla, an infectious diseases physician at St. Joseph’s Healthcare Hamilton and an associate professor of medicine at McMaster University, said Canada should be trying to find as many monkeypox cases as possible — especially as cases with no known links to travel emerge.
“That really does suggest that we’re only seeing the tip of the iceberg in terms of testing,” he told CBC News.
“You do want to make sure that testing is very broad until we’re able to link contacts more and more, and that we know where cases are coming from more and more, because at this point it doesn’t seem like it.”
When asked by CBC News whether the Public Health Agency of Canada (PHAC) is doing any random testing in the general community to look for cases outside of those presenting to physicians with symptoms, Tam said the agency is leaving it in the hands of doctors for now.
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“They’re watching out for rashes and of course the clinical history of contacts, but they are testing quite a lot of people who are actually testing negative for monkeypox but positive for other things,” she said.
“That’s one way of casting the net in the front lines of public health, and some of these individuals who are tested actually have very minimal skin lesions, but they are still being tested and we are finding other causes.”
Tam said PHAC is also looking at wastewater and other surveillance systems to detect cases of monkeypox and antibody levels in different populations, but she provided no specific details on when or if those initiatives would get off the ground to help track the spread.
“This is not like COVID, of course, it’s very difficult,” Tam said. “Many people have very non-distinct symptoms, but the rash is definitely a clue in this case.”
Vaccines are another important tool in preventing monkeypox from spreading in the community unchecked, and the National Advisory Committee on Immunization (NACI) is now recommending a single dose of the Imvamune smallpox vaccine for high-risk exposures.
But while some provinces such as Quebec have already begun vaccinating close contacts using a so-called ring vaccination strategy, with more than 1,600 doses administered so far, Canada has been tight-lipped on its stockpile of the vaccine at a national level.
“Affected provinces are currently implementing vaccination strategies based on their local epidemiology, and [PHAC] is currently working with manufacturers to ensure sufficient vaccine supply moving forward,” Tam said. “At this time, a mass vaccination campaign is not needed to address this outbreak in Canada.”
Unknown origins highlight dangers of spillover
Genetic analysis has shown that the strain of monkeypox circulating in Canada is the same one spreading internationally, but the origin of the outbreak in this country is still unknown.
“The spread is going to be slower than what we’ve seen with COVID, but I think obviously if we’re seeing cases that are not epidemiologically linked, there’s a problem,” Chagla said.
“That really is suggestive that a lot of these people could be missed, they could be continuing to transmit — and even if they do think they have it, there may be barriers for them to access care.”
Tam added that there was no known “singular event” that led to the explosion of cases in Quebec in particular, but multiple superspreader events may have occurred that have driven spread.
Canada hasn’t seen any deaths or severe cases of monkeypox yet, but Kindrachuk said that doesn’t “preclude risk” with the virus going forward if it keeps moving into different vulnerable sectors — such as homeless shelters, prisons and long-term care facilities.
“When we have infections that are continually accumulating, we know that we have populations and demographics within populations that have an increased risk for severe disease,” he said. “All of this hinges on containment.”
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Chagla said there could likely be “underrecognized spillover” into other social networks and high-risk close contact settings “where we could foresee a very real risk of ongoing spread.”
“We saw it with COVID, where it entered some of these high-risk places and took off like wildfire — and so I think that’s the major concern here,” he said.
“Having monkeypox take off in a homeless shelter, or having monkeypox take off in a correctional institution, can create huge havoc and lead to people that are already on the fringes getting pushed even further in that sense.”
Another major spillover risk experts are keeping an eye on is within the animal population because unlike smallpox, which was eradicated through vaccination largely because it was limited to human hosts, monkeypox has the potential to transmit back to animal reservoirs.
“We don’t fully understand what the reservoir host is or what other incidental hosts look like,” Kindrachuk said, adding that this key unanswered question plays a major role in the long-term containment of monkeypox and the possibility of it becoming endemic here.
“We certainly know it can move in other animals. We saw that in 2003 in the Midwest in the U.S., when it moved into prairie dogs. We know that it has been found in rodents and other animals in Central West Africa,” he said. “That net now has likely got to be cast beyond just humans.”
Dr. Scott Weese, chief of infection control at the Ontario Veterinary College at the University of Guelph, said animal spillover creating a new reservoir is the “big-picture concern” that could lead to prolonged spread and even mutation of the virus.”
“If we control it in people in Canada, it’s gone. Maybe it’ll come back, but it’s not staying,” he said. “If we get this into wildlife, then we get a situation where there’s going to be an ongoing risk — like there is in endemic areas of Africa.”