How contagious is mpox? Why scientists say this strain is ‘worrisome’ – National
Mpox has been declared a global public health emergency and while immunologists say more research is needed to determine how contagious it is, cases are being reported across communities and the virus is impacting not only adults but children as well.
Known as clade 1b mpox, the strain has been spreading across much of Africa since being first detected in the Kamituga region of the Democratic Republic of the Congo. Last week, a case was reported in Sweden in someone who had travelled to an affected African country, the first diagnosed outside of the continent.
David Kelvin, a professor in Dalhousie University’s department of microbiology and immunology and one of the lead researchers studying the Kamituga mpox strain, told Global News that what is “worrisome” is who it has impacted compared to 2022.
“Clade 2b started in a very defined social group and it moved through that social group,” he said. “Whereas this clade 1 is not defined to a single social group, it’s throughout the entire community.”
Clade 2b was the strain that caused a public health emergency in 2022, with concerns emerging at the time that it could stigmatize the LGBTQ2 community, as gay, bisexual and other men who have sex with men (MSM) between the ages of 18 and 49 were disproportionately affected.
Kelvin said the initial study showed some of the first cases being from heterosexual contact, however since discovery last year, he said a number of cases have been found in children as well.
Dr. Don Vinh, an infectious diseases specialist at McGill University Health Centre, told Global News that much like in 2022, caution should be taken on categorizing this latest form of mpox.
“As wrong as it is to say that the 2022 outbreak was a gay disease, which was completely wrong, that same logic would say that the clade 1b outbreak should be a straight disease, which of course is equally wrong,” Vinh said.
According to the Public Health Agency of Canada, evidence suggests that Clade I — of which clade 1b is a variant — is more transmissible and could potentially cause more severe disease than Clade 2. According to the U.S. Centers for Disease Control and Prevention, some outbreaks have killed up to 10 per cent of those who became sick, though recent outbreaks have had lower rates.
Earlier this year, the city of Bukavu, which is nearby Kamituga, had about six cases. That’s now grown to about 4,000.
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The primary method of mpox spread is close contact, typically skin-to-skin, with an infected person and the rash or scabs brought on by the virus. This can include sexual activities, but kissing and other social activities that are from close contact can also spread the virus.
Kelvin told Global News one reported case involved a hairdresser who was infected and who spread the virus when in close contact with clients while cutting their hair.
That close contact is also a worry with children as schools can be relatively crowded, including in regions of Africa where the virus is spreading.
“Children in close contact would be touching each other, spreading saliva, things like this,” he said.
Contact with saliva, respiratory secretions like snot and mucus, or bodily fluid or lesions around the genital area can also spread the virus. As well, the CDC notes that prolonged face-to-face interactions like talking or breathing in close proximity can also spread mpox, though it says this is due to respiratory droplets, not airborne spread.
Vinh said that while sexual contact may be one part of the spread, there could also be spread among household contacts, and in addition to that, there could even be cases of animal to human transmission — the CDC defines mpox as a zoonotic disease.
“So the combination of potentially sexual networks, non-sexual close contact networks and potentially even animal exposures, has us scratching our heads as to what the main drivers of transmission are,” he said.
Dr. Don Sheppard, vice-president of PHAC’s infectious diseases and vaccination programs branch, told Global News that clade 1 is often caused by such zoonotic transmission and can cause some spread in the community.
“Often within households, kids are the most affected because it’s very easy to spread inside household contacts,” he said. “The demographics of Congo are very different than they are here, where there’s a lot of younger people relative to older people, so kids tend to be involved.”
He added much like variants seen during the COVID-19 pandemic, the clade 1b variant having spread to several countries in Africa and now Sweden as well may signal that it is “better at spreading,” which could point to the potential for it to be more contagious.
People should also be wary of indirect contact, in which surfaces that have come in contact with an infected person and not been adequately disinfected could potentially infect someone else, Vinh said.
How to avoid catching mpox
The Clade 1 and clade 1b variant has not been detected in Canada as of Aug. 19, but there are still precautions that people can take.
The first is that should you decide to travel to one of the affected areas of Africa where mpox is endemic, stay away from crowded areas and use good public health measures like handwashing.
If you have no plans to travel, Vinh and Kelvin note the risk is low for infection but both say people eligible for the mpox vaccine should get it.
Kelvin said those at higher risk, such as due to immunodeficiencies or comorbidities, are among those he would recommend get the vaccine.
But Kelvin added that while there are indications this strain and its variant of mpox are more transmissible and thus potentially more contagious, more still needs to be done.
“We still need a lot of studies in order to handle this,” Kelvin said. “And with the surprising nature in how rapidly it can expand within a geographical location and then move to other geographical locations, we should probably be vigilant about seeing cases pop up.”
— with files from Global News’ Ella MacDonald and Katie Dangerfield
