The World Health Organization declared mpox was a global health emergency on Aug. 14, 2024, after the virus rapidly spread from the Democratic Republic of Congo to neighbouring countries. More than 17,000 suspected mpox cases and 517 deaths have been reported in the African continent so far, a 160 per cent increase in cases compared to the same period last year, according to Africa Centres for Disease Control and Prevention.
This is the second time the WHO has declared mpox a global health emergency in two years.
In Canada, Toronto public health officials have said there have been a spike in reported cases. As of July 31, a total of 93 cases have been confirmed this year, compared to 21 confirmed cases reported for the same period last year. The viral infection is not typically endemic in Canada, but the rise in cases has put infectious disease experts on alert in many parts of the world.
Here’s what you need to know about the virus, how it spreads and what steps to take to ensure you’re protected.
How is mpox spread?
Mpox, formerly known as monkeypox, spreads person-to-person in a variety of ways, including through contact with lesions or scabs or through bodily fluids, including blood, saliva or semen, according to the Public Health Agency of Canada.
It can spread between household members or people who have close sexual contact. PHAC notes that the virus can also spread in the form of respiratory droplets, when people are talking, breathing or sneezing in close proximity to another person.
How long does the virus live outside the human body?
Mpox is part of a family of viruses called poxviruses. These can survive in linens, clothing and on surfaces, particularly when in dark, cool, and low humidity environments, according to the U.S. Centres for Disease Control and Prevention. It notes on its website that one study found live virus in a patient’s home 15 days after it was left unoccupied.
But the mere presence of the virus doesn’t mean it will actually infect someone.
Stephen Hoption Cann, a clinical professor at the University of British Columbia’s school of population and public health, advised not to think about mpox in the same way as COVID-19.
Unlike COVID-19, people cannot catch the virus at a grocery store, at a restaurant, or through shared transportation. “This is not really how you’re going to contract this disease,” Dr. Hoption Cann added.
How easily does mpox spread?
Infectious disease specialist Allison McGeer said people cannot catch mpox from casual contact with contaminated items, like trying on clothing in a store, or from inadequately washed bedding at a vacation rental.
Prior to the 2022 outbreak, data from African countries – where mpox is endemic – had indicated the virus was not very transmissible, said Dr. McGeer, a member of the Emerging and Pandemic Infections Consortium and a professor at the Temerty Faculty of Medicine at the University of Toronto.
The current outbreak in Congo began with the spread of an endemic strain, known as clade I. But a new variant, clade Ib, appears to spread more easily through routine close contact, including from mothers to children. The vast majority of deaths globally have occurred among children.
In Toronto, public health authorities said mpox is currently spreading mostly between people who have close, intimate or sexual contact with a person who has the virus. Gay, bisexual and other men who have sex with men are most affected.
How long does a person remain infectious?
People are believed to be infectious for roughly two to four weeks, from when symptoms first start to until when their skin fully heals and all the scabs from their lesions or rashes fall off, Dr. Hoption Cann said.
It’s difficult to determine whether people without symptoms can transmit the virus because individuals could unwittingly pass it on if they have a lesion in the mouth or genital area, where it may not be obvious, he said.
He added that the cases occurring now may only cause one lesion, whereas patients in photographs may have hundreds.
Ideally, people should be isolating while they’re infectious, but he said if they must go out in public, they should cover up any area that has a rash or lesion.
Who should get tested and vaccinated?
The primary focus for testing and vaccination is on gay, bisexual and other men who have sex with men, since most infections are currently among this demographic, Dr. Hoption Cann said. Individuals who have had multiple sexual partners, who are not using condoms or have a lot of intimate contact with others should get tested or vaccinated, he said.
However, Dr. Hoption Cann also noted the disease’s spread outside this demographic.
Toronto Public Health is recommending eligible residents to get two doses of the mpox vaccine to provide the best protection, and that the second dose to be taken 28 days after. Eligible residents include individuals who are engaged in sex work or those who self-identify as having sex with gay, bisexual, pansexual, and other men who have sex with men. They also need to meet at least one of the following criteria: had a confirmed sexually transmitted infection within the last year; have or are planning to have two or more sexual partners; have attended, worked at or are planning to visit venues for sexual contact, such as bath houses; had anonymous sex or are planning to; are in contact with a sex worker. The Toronto Public Health’s website lists the full criteria.
Globally, mpox has been reported in some women and children in countries where the virus has not been previously seen, though they still make up a small proportion of cases.
Canadians can get tested for mpox based on a number of factors, including having signs and symptoms of the disease or being exposed to a case, according the Public Health Agency of Canada. Since mpox can appear similar to chickenpox or sexually transmitted infections, such as herpes and gonorrhea, it advises people to consult a health provider and get tested.
Provinces and territories are maintaining individual webpages with testing and vaccination information.
Canada not planning to share mpox vaccines, as Africa warns of ‘another pandemic’
How long does it take for the mpox vaccine to start to work?
This is still unknown. There are many questions about the timing and protection of the vaccines since those now being used for mpox were created for smallpox, Dr. McGeer said.
Even though the vaccines have been tested against mpox, these tests were conducted at a time when there wasn’t enough of the disease circulating to be able to do vaccine efficacy studies, she said. Research in animals and immunogenicity studies that measure the immune response in humans do indicate the vaccines are effective against mpox, she added. And there is some indication people do benefit from a single dose.
“But we really do not know how effective these vaccines are,” she said.
How much protection does someone have against mpox if they were vaccinated for smallpox decades ago?
This, too, is unknown. According to New York State’s Department of Health, smallpox vaccination provides full immunity for three to five years, after which immunity declines.
At this stage, it’s hard to say how much immune protection Canadians who were given a smallpox vaccine now have against mpox, Dr. Hoption Cann said. Canada stopped routine vaccination against smallpox in 1972.
“If a person was at high risk, I wouldn’t depend on the vaccine received that many decades ago to protect them,” he said.
Toronto Public Health is recommending that if an at-risk or eligible resident has received a smallpox vaccine in the past, they should still get vaccinated for mpox.
Since this article was originally published, the WHO changed the name of the virus from “monkeypox” to “mpox”. The Globe has updated this reporting with the new name.