Canada’s chief public health officer said Friday provincial health authorities are investigating “a couple dozen” possible cases of monkeypox — and most of the specimens under review are from Quebec, where two cases have been confirmed already this week.
Speaking to reporters on Parliament Hill, Dr. Theresa Tam said the National Microbiology Lab in Winnipeg is running tests on samples from Quebec and B.C., and it’s possible that some of those suspected cases may be confirmed as monkeypox in the coming hours.
“We don’t really know the extent to which the spread has occurred in Canada. So that is an active investigation,” Tam said. “What we do know is that not many of these individuals are connected to travel to Africa, where the disease is normally seen.”
Tam said the overall risk to the population is “low” at this point but researchers are working now to determine why monkeypox — a disease usually confined to Central and West Africa — seems to be in circulation here in Canada and elsewhere in the Western world.
“This is unusual,” Tam said. “It’s unusual for the world to see this many cases reported in different countries outside of Africa. So I think we’ll let people know as soon as we get more information.”
Monkeypox is a viral zoonotic disease that occurs primarily in tropical rainforest areas. Historically, most cases have been reported in the Congo Basin.
There are two main strains or “clades” of monkeypox: the Congo strain, which is more severe — with up to 10 per cent mortality — and the West African strain, which has a fatality rate of about one per cent.
Symptoms can include fever, intense headache, swelling of the lymph nodes, back pain, muscle aches and a lack of energy. People who are infected can also develop a rash and lesions.
Monkeypox transmission can result from close contact with “respiratory secretions” or skin lesions of an infected person or recently contaminated objects.
According to the World Health Organization (WHO), transmission via respiratory particles usually requires “prolonged face-to-face contact” — which means health workers, family members and other close contacts of active cases are at greater risk than the public at large.
Smallpox and monkeypox belong to the same “family” of viruses, said Dr. Howard Njoo, Canada’s deputy chief public health officer. As a result, the smallpox vaccine has proven effective against its monkeypox “cousin” in the past.
But the smallpox vaccine has not been in circulation in Canada for decades because smallpox was eradicated here in the late 1940s. The World Health Organization (WHO) declared it globally eradicated in 1979.
That means younger people may be more susceptible to monkeypox because the smallpox shot wasn’t part of their childhood immunization schedule.
“We’re all susceptible and to be quite honest, the good practices that we learned with COVID-19 serve us in good stead against a whole host of diseases, including this one,” Njoo said.
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Tam said Canada does have an unspecified number of some smallpox vaccine doses on hand. She said she couldn’t say how many are available due to “security” concerns.
Smallpox vaccine doses have been carefully guarded in Canada because of lingering fears about an accidental release of the virus and the risk that it could be used for nefarious purposes like terrorism.
Tam said that, after liaising with federal authorities, Quebec is considering deploying those shots in some areas of the province where cases have been reported.
Unlike influenza or COVID-19, monkeypox has a long incubation period. The time from infection to symptoms is usually seven to 14 days but it can range from five to 21 days. That means vaccines can be used effectively on people who may be likely to develop monkeypox after being a close contact of an active case, Tam said.
Dr. Michael Libman, director of the J.D. MacLean Centre for Tropical Diseases at McGill University, said the spread of monkeypox is a “prime example of how expanding human encroachment into animal habitats, that had previously been isolated, leads to transmission of animal infections to humans.”
“The return of high-volume travel and close interactions of large numbers of people has once again allowed for an astonishing rapid propagation around the world,” Libman said.