Australia is bracing for rising numbers of monkeypox cases in the warmer months, but experts say the epidemic is not a cause for panic because evidence shows the outbreak is being fuelled almost entirely by sexual transmission.
Professor Andrew Grulich, a lead in Australia’s HIV response, said the outbreak had so far largely affected men who have sex with men and the risk of the broader population contracting the disease remained low.
A patient receiving the monkeypox vaccine at a walk-in clinic in North Jersey. Credit: AP
“The first thing I’d say is that the general community, who are not homosexual and bisexual men, really don’t need to be worried about catching monkeypox at the moment,” Grulich said.
“Epidemiologists are keeping a very close eye on transmission patterns to make sure that this stays the same, because, certainly, bisexual men transmitting it to their female partners is possible, and we should be concerned about it.”
However, Grulich noted there was strong international data, particularly from the UK and US, suggesting the pattern of transmission of monkeypox remained constant between early June and August, despite cases rising quickly globally.
“Thus far, only about 1 per cent of cases of monkeypox are in women. The numbers are extremely low,” Grulich, a Kirby Institute researcher, said.
“In fact, in England and the US, where this has been looked at closely, a very substantial proportion of that 1 per cent is actually transgender women, which really points strongly towards it being social and sexual connection with gay men, rather than the bisexual men and women.”
Researchers globally are also trying to determine if monkeypox can spread via semen. A recent study published in The Lancet Infectious Diseases suggested that semen with the virus may be able to infect human cells.
Professor Andrew Grulich.Credit: SMH
Australian men who contracted monkeypox are being urged to wear a condom during sex for about two months after their lesions heal.
“Not having new sexual partners while you have monkeypox is very important,” Grulich said. “After the lesions have healed, people should continue to use condoms for eight weeks because of some preliminary evidence that the virus might be in semen. That’s important and undisputed at the moment.”
Victoria’s Health Department said monkeypox could spread through skin-to-skin contact, large respiratory droplets or contact with contaminated items or surfaces.
Grulich said preliminary data showed, while other modes of transmission were possible and anyone could be infected, the virus didn’t appear to spread well through non-sexual routes.
About 0.2 per cent of people infected caught the virus from a contaminated surface in this outbreak, the World Health Organisation reported this month.
Cases of the monkeypox virus in Melbourne have surged recently, and health officials remain unable to explain the emergence of about 20 locally acquired mystery cases of the infectious disease.
There have been about 91 monkeypox cases nationwide since May, including 40 in Victoria.
As the outbreak grew, so too did confusion about the virus, how it spreads and who is currently at high risk for being infected.
The evidence so far suggests airborne transmission – a common route of spread for viruses such as COVID-19 – remains rare for monkeypox. This meant catching the virus on public transport, for example, would be highly unlikely.
“If it was being transmitted on buses or in other crowded environments like dance floors, then we would have seen transmission to women and heterosexual men across the world, and it’s just not happening,” Grulich said.
He pointed to several pride parties in Europe, thought to be ground zero of the global outbreak, where cases originated from sexual encounters, despite thousands of people congregating closely together on dance floors.
“Crowded dance floors ... you could not get a better place for airborne transmission, and we just saw no evidence of that,” he said.
Typically, monkeypox causes fever, chills, rash and lesions on the face or genitals. Most people recover within several weeks without requiring hospitalisation.
Australian public health guidelines say those diagnosed with the infectious disease should isolate at home for three weeks and ensure all their lesions have completely cleared up before they have sex.
In the US more than 98 per cent of those infected have been adult men who acquired the virus through intimate contact with other men — and so far less than a dozen pediatric cases have been recorded.
In parts of Africa where monkeypox is considered endemic, cases among children are not unusual, but Grulich said the risk of monkeypox to Australian children was low.
“Monkeypox would not be the first virus to spread differently in high-income countries than it does in low-income countries,” he said, adding there was a far higher prevalence of skin infections in places like Africa.
Grulich said Australia has a chance to get ahead of the outbreak in the next few months with a community-led response.
“We should absolutely use the amazing HIV prevention infrastructure that we’ve developed over 40 years in this country,” he said.
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