The World Health Organisation has declared mpox (formerly called monkeypox) a global health emergency driven by a new strain in Africa, amid warnings the virus threatens to spill across international borders.
Mpox is a serious infectious disease.Credit: AP
What is mpox and how do you get it?
Mpox is a viral zoonotic disease (meaning it is transmissible between animals and humans) in the same family as the virus that caused smallpox. Scientists first identified it in 1958 when there were outbreaks of a “pox-like” disease in monkeys, and it was identified in humans in 1970 in the Democratic Republic of Congo.
Until recently, most human cases were seen in people in Central and West Africa who had close contact with infected animals, but in 2022, scientists confirmed mpox was spreading via sex between humans for the first time, and outbreaks were detected in more than 70 countries that had not previously reported the virus.
Mpox can spread through:
- Direct skin-to-skin contact with rashes, blisters or sores on the skin
- During sex, via semen and other bodily fluids
- Contaminated objects, such as bedding or clothes
- Breathing in droplets breathed out by someone who has mpox, but this is rare.
A person with mpox can be infectious from the time they develop symptoms until all scabs have healed and a fresh layer of skin has formed, which may take several weeks.
What does mpox do to you?
Mpox usually causes mild symptoms including fever, chills and body aches, headaches, joint pain and exhaustion.
More serious cases can cause a distinctive rash, which eventually forms a scab and falls off. It can also appear as lesions (bumps that turn into pimples, blisters and sores, which may burst to form ulcers). They look similar to chickenpox but are larger and can vary in size and number from a single lesion to several thousand.
The rash and lesions can occur on any part of the body, including the face and inside the mouth, the torso, arms and hands, legs and feet, and the genital and perianal areas. They can be painful, especially if the lesions join or appear in the mouth or rectum.
Symptoms begin five to 21 days after exposure to the virus. For most people, symptoms will clear up on their own after two to four weeks.
If you are a suspected case, you should isolate yourself until you return a negative result.
Which groups are most at risk?
Broadly speaking:
- People who have had close physical contact with a mpox case
- Australian travellers to and from countries with confirmed cases
Key risk groups are gay, bisexual and other men who have sex with men, sex workers and their sexual partners.
Infants, young children, pregnant women and people who are immunocompromised are at higher risk of becoming severely unwell if infected.
Is there a vaccine?
There is a vaccine available in Australia called JYNNEOS. It is free and recommended for eligible groups:
- All sexually active gay and bisexual men (cis and trans)
- Sex workers
- Sexual partners of the people above
The vaccine comprises two doses given at least 28 days apart for people 18 years and over.
Professor Andrew Grulich, who is head of the HIV epidemiology and prevention program at the Kirby Institute, UNSW Sydney, said the fast rollout of mpox vaccines in 2022 triggered rapid declines in transmission.
“In Australia, vaccine rollout in gay and bisexual men averted a serious epidemic associated with the global gathering of LGBTQI+ people at the Sydney World Pride festival in early 2023,” Grulich said.
The vaccine is most effective two weeks after the second dose and gives 80 per cent protection against mpox. There is still a risk of infection with the virus that causes pox, but if you are vaccinated, it may mean you only experience mild symptoms.
Why has the WHO declared it a global health emergency?
WHO director-general Tedros Adhanom Ghebreyesus made the declaration on Wednesday after the Africa Centres for Disease Control and Prevention declared mpox a public health emergency on the continent.
There have been more than 14,000 cases and 524 deaths in Africa this year, which already exceeds last year’s totals. More than 96 per cent of all cases and deaths are in a single country: Congo.
“Mpox is a slow-burning fire that has been allowed to smoulder in Central Africa and is flaring up again. This time the WHO is ringing the alarm,” said David Tscharke, a poxvirus researcher from the John Curtin School of Medical Research at the Australian National University.
Professor Adrian Esterman, chair of biostatistics at the University of South Australia, allied health and human performance, said a new strain of mpox was raising concerns because it was more easily transmitted and could potentially cause more severe disease than the strain circulating in 2022.
“This development has prompted the WHO to take decisive action, highlighting the need for increased vigilance and international co-operation to prevent further spread,” Esterman said.
Grulich said it was a global imperative to get vaccines to African communities. “If we want to avoid this condition becoming deeply established around the world, it needs to be controlled in Africa,” he said.
Is there a risk in Australia?
There has been a re-emergence of mpox in Australia, with 241 confirmed cases in 2024 so far compared with just 26 cases in 2023. Cases are concentrated in Sydney and Melbourne, with NSW reporting 93 cases and Victoria 108 cases so far this year, but spread across the country. All but one of the cases are in men.
Surveys suggest about half of all men who have sex with men are vaccinated.
Grulich said the rising case numbers indicate vaccination levels are sufficient to stop major epidemics, but too low to prevent small chains of transmission.
“Importantly, the strain that has led to a public health emergency in Africa has not been detected in Australia yet,” he said.
Start the day with a summary of the day’s most important and interesting stories, analysis and insights. Sign up for our Morning Edition newsletter.