Heard about monkeypox? Experts say that, while it's being picked up in an increasing number of countries, there's no need to panic. Science reporter Jamie Morton explains three things you need to know about it.
It's on the rise – but it's not new
If this is the first time you've heard about a viral disease called monkeypox, you won't be alone.
While it was first reported in humans way back in 1970, it's rare, and has generally been confined to tropical rainforest areas in Central and West Africa.
Scientists have observed a gradual resurgence over the past decade - but it's been just in the last few weeks that more than 100 fresh cases have been reported as far and wide as Israel, Sweden, Spain, the US and Australia.
In the UK, where around 20 cases have been reported, there are concerns the virus may be transmitting after officials confirmed infections in people with no record of travel to regions where it's endemic.
If the virus was indeed spreading in Britain, Canterbury University epidemiologist Associate Professor Arindam Basu said, then it should put countries on higher alert over any identified cases – including a reopening New Zealand.
"The tell-tale signs to look for are fever, flu-like symptoms, and appearance of rashes," he said.
"Watch out for people starting with flu-like symptoms, negative for Covid-19 and then developing a rash a few days later."
The risk is currently considered low
We know of two main varieties of monkeypox: a deadlier type that comes with a fatality rate of about 10 per cent, and another, less severe type that kills only about 1 per cent of those it infects.
While we fortunately don't appear to be dealing with the former, it's still not clear if the world is seeing a new strain.
"We still don't have much data on this," said Dr Vinod Balasubramaniam, a molecular virologist at Monash University Malaysia.
"The fact that so many cases are being reported in several countries certainly suggests that this strain is more transmissible than others.
"We still need to look at the current genomic data on the currently circulating strain to know more."
While severe cases could occur, it was currently considered a self-limiting disease, with symptoms lasting from two to four weeks.
"It is less contagious than coronavirus and the outbreaks are much smaller," Otago University biochemist Professor Kurt Krause said.
Along with having a much longer incubation period – six to 13 days, compared with Omicron's two to four days – monkeypox was also less contagious because it caused a large number of visible lesions.
"So inadvertent transmission is less likely," Krause said.
"However, transmission is possible, it's just that the [reproduction number, or R0] values are often found to be less than one and the outbreaks die out."
Experts were particularly interested to find out whether the virus could be spreading in humans through sexual intercourse – a theory being investigated by the World Health Organisation.
"The literature says monkeypox is transmitted through droplets and saliva," infectious disease and sexual health physician Dr Massimo Giola said.
"But the virus also causes lesions and could transmit through close skin to skin contact. And even kissing could cause transmission through saliva."
Krause said it would be important to determine the R0 from this latest outbreak, and to fully sequence and analyse this virus.
"However, in the absence of a major genomic change, or a major shift in R value it is unlikely to cause a major outbreak and it unlikely to cause a major outbreak here."
It's very different to Covid-19
As its name implies, monkeypox is a pox virus and part of the same, diverse family of oval-shaped viruses that includes the notorious smallpox.
Since smallpox was globally eradicated just over four decades ago – it remains the only human disease we've managed to wipe out from nature - monkeypox has become the most common cause of pox infections.
While the Sars-CoV-2 virus that causes Covid-19 is also zoonotic – or stemming from animals – it's much unlike monkeypox.
One of the biggest differences is monkeypox is a double-stranded DNA virus, and thus has a larger and more stable genome than coronavirus, a single-stranded RNA virus.
As a global public health threat, the coronavirus clearly dwarfed it, having caused hundreds of millions of infections and millions of deaths - that we know of.
Associate Professor Fasséli Coulibaly, a microbiologist at Australia's Monash University, said pox viruses were among the most complex viruses able to infect humans - and were experts at subverting defence systems put up by their host.
"Yet, they are a bit like the elephants of the virus world," he said.
"Their structure and replication make them easier to aim at than smaller, moving targets."
Indeed, decades of basic research had revealed a few chinks in their armour.
Seeing a lot of folk tweeting about monkeypox. Some are experts on COVID19 but not all have experience of emerging disease outbreak investigation. So here are some thoughts.— Helen Ward (@profhelenward) May 22, 2022
- It’s not Covid
- Control will be different
"This has prepared us well to respond to such a threat as drugs and next generation vaccines have been developed against smallpox, providing options to respond to monkeypox should it develop further."
Some scientists suspect our waned immunity to a long-absent smallpox may have raised our vulnerability to monkeypox.
The good news is the world does have effective vaccines available: the second and third generation smallpox vaccines, both of which are "live virus" vaccines using the vaccinia virus.
Otherwise, the Ministry of Health advises people to practice good hand hygiene after contact with infected people or animals, and avoiding contact with any materials, like bedding, that have been contact with them.
People returning from overseas with any blister-like sores on their bodies, or experiencing a rash-like illness, were also asked to seek healthcare advice.
While the monkeypox risk might be currently deemed low, scientists still say health authorities should be paying close attention.
"One thing for sure is that, the threat posed by this virus should not be taken lightly and increased surveillance and vigilance is definitely needed," Balasubramaniam said.
"In light of the current environment for pandemic threats, the public health importance of monkeypox disease should not be underestimated."