The monkeypox virus, which causes fever symptoms and rashes, has been detected in countries across Europe and North America.
The virus occurs primarily in tropical rainforest areas of Central and West Africa – but now dozens of confirmed or suspected cases are being investigated in several countries including Spain, the UK, the US, and Canada.
The SMC asked experts to comment on the virus and the risk it poses to NZ.
Arindam Basu, Associate Professor of Epidemiology, School of Health Sciences, University of Canterbury, comments:
“Monkeypox has made a resurgence recently. It is usually considered to be ‘endemic’ for Central and West Africa; but since 2013, an increasing number of cases are being seen worldwide. There has been a recent rise in the number of cases in Europe (20 cases in Portugal as of yesterday, and 9 cases in the UK) plus a number of cases being investigated in the US and Canada.
“Unfortunately, it is believed that in the UK, the cases may be ‘endemic’ (as of this writing, but this may change in future). If this is true, then it should raise concerns about their identification in other parts of the world, notably in New Zealand as well, as we are now connected to the rest of the world with borders reopening.
“The tell-tale signs to look for are fever, ‘flu-like symptoms’, and appearance of rashes. The disease itself is self-limiting, and unfortunately, at the moment no one is vaccinated (smallpox vaccination is not routine anymore). The incubation period is 6-13 days; the main routes of transmission are sharing of body fluids, skin lesions, and droplet transmission (so close contacts and healthcare workers are at risk). Watch out for people starting with flu-like symptoms, negative for COVID-19 and then developing a rash a few days later.”
No conflict of interest.
Dr Massimo Giola, infectious disease and sexual health physician, comments:
“Monkeypox is a relative of the smallpox virus, which was eradicated through a worldwide campaign of mass vaccination. So all people who were born before 1970 have been vaccinated against smallpox. We know there are two different strains of monkey pox virus. The Western African strain, the one detected in this outbreak is the milder strain, so I guess this is good news.
“What caught my attention immediately as soon as I was made aware about this, is that most of the cases at the moment seem to occur among gay and bisexual men. We know that gay and bisexual men are a canary in the coal mine of infectious diseases, and particularly sexually transmitted diseases. The reasons for that are quite complex.
“Sexual health surveys have shown that there is not a big difference comparing gay and bisexual men with the heterosexual population, in terms of the total number of sexual partners during their lifetime. What is slightly different is that gay and bisexual men tend to have slightly more concurrent partnerships, which means having more than one sexual partner at any given time, whereas heterosexual people seem to have more serial sexual partnerships. With a sexually communicable disease, that makes it possible to infect more than one person, allowing the epidemic to expand.
“Gay and bisexual men are also a minority in the general population, which means our sexual networks tend to be much more dense. As we say in the gay world, we are all family. That obviously means if you get an STI into those dense sexual networks, then that will spread like wildfire, much more than in the heterosexual population.
“There are also reasons related to stigma and discrimination. So that means people having to go to dedicated places like gay clubs or saunas where lots of men will congregate in a short time in a small place where transmission will be easier. People may also not want to come forward for a health screening, because of the stigma and discrimination they might feel in the healthcare setting.
“Another thing I’d like to mention is around gay men and international travel. A number of reasons – that range from having more disposable money, not having kids, to having a more widespread international network of dedicated places to go to for holidays – make it very easy and very fast to spread infections among gay and bisexual men over the four continents. By the time this cluster had been detected, it’s very likely that monkeypox was already across the four continents. I think it’s only a matter of time before we have the very first cases in Australia or New Zealand.
“There is a question around whether monkeypox is sexually transmitted. The literature says monkeypox is transmitted through droplets and saliva. But the virus also causes lesions and could transmit through close skin to skin contact. And even kissing could cause transmission through saliva. There are a few diseases (eg scabies, meningococcus) like this that, given the right circumstances, behave like sexually transmitted diseases even though they’re not normally classified in that group.
“One thing to be aware of is that in the sexual health clinics, if we see someone with a rash, including lesions on the palms and the soles, we immediately think syphilis. The problem is that monkeypox gives you exactly the same presentation. The only clinical characteristics that seems to differentiate monkeypox from syphilis is that typically in syphilis, the lesions are not painful. Whereas in monkeypox – from the little we know about it – the lesions seem to be exquisitely painful.”
No conflict of interest declared.
Professor Kurt Krause, Infectious Diseases Physician; Professor of Biochemistry, University of Otago, comments:
“Monkeypox is, like the name implies, a poxvirus. It is quite closely related to smallpox and in fact is now the most frequent cause of human pox infections. Most monkeypox infections occur in Africa but there have been sporadic outbreaks before e.g., a 2003 prairie dog-related outbreak in the USA.
“It is very different from coronavirus in many ways. It is a double-stranded DNA virus, unlike coronavirus which is single-stranded RNA. It has a much bigger genome than coronavirus. Its genome is more stable as well. It is generally passed by contact but droplets are possible but less common. It is less contagious than coronavirus and the outbreaks are much smaller. There are two main varieties – one is more dangerous with a fatality rate of about 10 per cent and one caused less severe disease with a fatality rate of 1 per cent or less.
“One reason the disease is less contagious is because people are often stricken with a very large number of quite visible pox lesions and it is then readily apparent that the affected person is ill. So inadvertent transmission is less likely. However, transmission is possible, it’s just that the Ro values are often found to be less than 1 and the outbreaks die out.
“The new cluster of cases is quite interesting because of the link to possible sexual transmission. It will be important to determine the Ro 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.”
No conflict of interest declared.