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Australia has recorded its first case of the mpox variant that typically causes more serious illness.
The Australian Centre for Disease Control (CDC) confirmed a case of mpox clade 1b in NSW earlier this month — the first, and so far only, case of this variant in Australia.
The case was a returned traveller, and the risk of further transmission was low, a spokesperson for the federal Department of Health said.
A spokesperson for NSW Health said the case was a man who contracted the virus while holidaying in Thailand.
The spokesperson said the man had developed symptoms after arriving back in Australia and has since recovered.
What is mpox?
Mpox is a viral zoonotic disease, and comes from the same family as the one responsible for smallpox.
It is divided into two clades, clade 1 and clade 2, and further into two subclades: 1a and 1b, and 2a and 2b.
Historically, clade 1 is more likely to cause severe illness and death than clade 2.
Mpox is endemic to parts of central and West Africa, according to the United States Centers for Disease Control and Prevention. But in 2022, a global outbreak of clade 2 occurred, which is ongoing.
There have been 1,726 confirmed cases of mpx across Australia since 2022, according to the Department of Health’s National Notifiable Disease Surveillance System. The majority of these (1,409) were recorded in 2024, and there have been 147 cases so far this year.
Until the recent clade 1b case, reported infections in Australia have been caused by mpox clade 2b, the CDC states. It says most of these infections were locally acquired.
It says mpox clade 1b infections were previously isolated to Central Africa but have since been recorded elsewhere. The World Health Organization (WHO) lists a small number of countries outside Africa where clade 1b cases have been recorded, including, along with Australia, the United Kingdom, Germany, Thailand, France, the United Arab Emirates, and Switzerland. It says reported cases in these countries are linked to travel and not local transmission.
More than half of the 32,953 reported clade 1b cases recorded in parts of Africa since January 2024 have been recorded in Democratic Republic of the Congo, according to the WHO.
The CDC acknowledges clade 1 has generally been considered to cause more severe disease, but recent data suggested clade 1b — first discovered in 2023 — has a fatality rate similar to clade 2b. The US Centers for Disease Control and Prevention also notes recent outbreaks have seen “much lower death rates”.
What are the symptoms of mpox?
Signs and symptoms can include a distinctive rash or lesions, swollen lymph nodes, headache or fever, muscle aches, joint pain, back pain, chills and exhaustion.
The virus can be transmitted through intimate or prolonged physical contact, close contact with rashes on the skin, body fluids (including droplets from coughing or sneezing) and contaminated objects such as linen and towels.
Symptoms typically clear after two to four weeks for most people, but some can become seriously ill.
The Department of Health says most cases in Australia have been identified in gay, bisexual and other men who have sex with men, but anyone can be affected.
It says that most infections are mild.
Eligible groups can receive free vaccinations against mpox, with no Medicare card required.
Vaccination is recommended for men who have sex with men, sex workers, and healthcare and laboratory staff at risk of exposure.
Those who have close physical contact with an infected person or are immunocompromised are also considered high risk.
Anyone at risk who plans to travel to a country experiencing a significant outbreak should be vaccinated four to six weeks before travelling.
The best time for people to receive the vaccine is before they are exposed to mpox.
