Mpox strain spreading in African countries could arrive in Canada, doctors say

The type of mpox spreading rapidly through several African countries could arrive in Canada, where that strain hasn’t appeared before, Canadian experts say.

The detection of clade I mpox in Sweden in someone who had travelled to an affected African country is a “harbinger” of broader spread, said Dr. Fahad Razak, an internal medicine specialist and epidemiologist at St. Michael’s Hospital in Toronto. 

The Public Health Agency of Sweden said Thursday it is the first case of clade I mpox to be diagnosed outside the African continent. 

Razak said he wasn’t surprised to learn about the case. 

“It was only a matter of time,” he said in an interview. “Canada being a major port of travel globally — we’re one of the most travelled high-income countries in the world… I think we should expect that cases will occur here.”  

The World Health Organization’s declaration on Wednesday that mpox is a public health emergency of international concern was partly based on the surge of clade I in Congo and its appearance in nearby Burundi, Kenya, Rwanda and Uganda — four countries that had not had mpox of any kind before.

Clade I mpox appears to be more transmissible and more severe than the clade II variant that caused an epidemic in Canada in 2022, Razak said.

Many of the cases of clade I mpox are children, he said. 

The good news is that mpox may not spread as easily as COVID-19 did when it first arrived, so Canadian health agencies would likely have an easier time containing it, said Razak, who was the scientific director for Ontario’s COVID-19 Science Advisory Table. 

“It is still a disease that seems largely to be transmitted through direct contact rather than airborne (transmission). And that means that control measures can work really well,” he said. 

The other good news, Razak said, is that there is a vaccine for mpox. 

Dr. Allison McGeer, an infectious diseases specialist at Mount Sinai Hospital in Toronto, said we need to learn more about the epidemiology of clade I mpox before the sense of what to expect in Canada becomes clear. 

McGeer noted that we didn’t get any Ebola cases in Canada during the west African outbreak about a decade ago. 

If clade I mpox is mostly spreading in rural areas from animals and within households — and if there’s not a lot of travel happening in those settings — Canada may not see cases, or only a few of them, she said in an email on Thursday.  

“(But) if it has evolved to be more transmissible, we’ll start to see travel-related cases,” McGeer said. 

The Public Health Agency of Canada said Thursday it is “aware of reports of a case of clade I mpox virus identified in Sweden” and confirmed that there have been no such cases in Canada to date. 

“As part of its routine preparedness activities, PHAC is working with Global Affairs Canada and partners to update risk assessments, public health guidance, and travel health advice for mpox as appropriate,” it said in an emailed statement. 

The agency also said it’s working with provinces, territories and the World Health Organization to do surveillance of mpox in Canada and “maintain vigilance for the emergence of clade I monkeypox virus” here. 

Canada is able to test for both clade I and clade II mpox and has been doing wastewater surveillance since July 2022, the agency said. 

It is also monitoring an increase in clade II mpox cases in Toronto and encourages people who are eligible to get two doses of the mpox vaccine. 

Clade II mpox spreads through “close/intimate or sexual contact with someone who has the virus or contact with surfaces/materials that may have the virus,” according to the Toronto Public Health website. 

Men who have sex with men are eligible for vaccination if they have or are planning to have two or more sexual partners, have attended venues for sexual contact, have had or are planning to have anonymous sex, are a sexual contact of someone who does sex work, or has had a confirmed sexually transmitted infection in the past year, the website says.  

Anyone who does sex work, regardless of self-identified sex or gender, is eligible to receive the vaccine, the website says.  

Household members or sexual contacts of those listed above who are immunocompromised or pregnant may also be eligible for mpox vaccination. 

People who have had close contact with someone with mpox may be able to get a post-exposure vaccination. That should ideally be given within four days of exposure but can be administered up to 14 days after the last exposure, the website says.