Dr David Heymann, who used to head the WHO’s emergencies department,
Monkeypox may have been spreading under the radar for four years, an ex-World Health Organization (WHO) official has claimed.
Professor David Heymann, a former former director-general for health security and environment at the WHO, said the current global outbreak may date back to a handful of isolated cases in the UK in 2018.
Two Britons were diagnosed with the tropical disease in September 2018 after returning from Nigeria. A third case was found in an NHS worker who treated one of the patients.
In December 2019, a fourth person unrelated to the previous three tested positive for the virus after returning from Nigeria. Three further cases with similar travel history arrived in 2021.
Professor Heymann suggested the virus may have been seeded in around this time and spread unchecked. All of the cases are believed to have had the milder western African clade of the virus — the same one that is spreading now.
He told The Guardian: ‘It could hypothetically be that the virus transmission amplified from this low level of transmission when by chance it entered the population that is at present amplifying transmission.’
But he said this was just one of several theories that needed to be investigated before coming to any conclusions.
It comes as Wales and Northern Ireland reported their first cases of monkeypox in the latest outbreak, bringing the UK total to 80.
UK health chiefs are understood to be planning an online dashboard that tracks case numbers — a method which sparked controversy during the coronavirus pandemic.
Scientists are currently studying the virus’s genome — its genetic material, gathered from swabs taken from infected people — which allows them to track mutations.
Analysis so far suggests the virus is closely related to the one detected in the UK, Israel and Singapore in 2018 and 2019.
Professor Marc Van Ranst, a virologist at the University of Leuven in Belgium, suggested the virus may have mutated to become more infectious, which would explain the sudden rise in infections.
He told the Guardian: ‘This may be a virus that’s been circulating undetected for quite a while.
‘They all have a common ancestor and that common ancestor probably dates back to 2019, though it’s too early to date with any kind of accuracy.
‘We know that chronic infection is not a plausible scenario, and that means there has been a chain of transmission events that apparently went unnoticed.’
Professor Van Ranst said it was ‘entirely possible’ that the virus may have been continued to be transmitted in the UK if GPs and sexual health clinics were not on high alert after being informed of the first case.
A team of scientists in Portugal, who are tracing the virus’s evolution, said that while the virus is very similar to one that cropped up in Britain four years ago, it has collated an extra 50 mutations.
The researchers, from the country’s National Institute of Health in Lisbon, wrote that this was ‘far more than one would expect considering the estimated substitution rate for orthopoxviruses’.
They also warned that an ‘evolutionary jump’ — like with the Covid Omicron strain — may have created a ‘hyper-mutated virus’.
Professor Oyewale Tomori, a virologist and adviser to the Nigerian government, agreed that monkeypox may have been ‘spreading silently’ until now.
He told the Guardian: ‘Between 2019 and 2020 if anybody came up with a rash in any part of Europe, you’re not going to think of monkeypox, your thought would be other diseases that cause a rash.
‘And if the system misses that one case, then of course that’s an opportunity for it to spread from one person to another. I think the amplification came where you have a lot of people gathering with very close contact.’
Experts this week said the virus may have been sparked by sex at two raves in Belgium and Spain.
Professor Heymann said: ‘We know monkeypox can spread when there is close contact with the lesions of someone who is infected, and it looks like sexual contact has now amplified that transmission.
‘It’s very possible there was somebody who got infected, developed lesions on the genitals, hands or somewhere else, and then spread it to others when there was sexual or close physical contact.
‘And then there were these international events that seeded the outbreak around the world, into the US and other European countries.’
Despite not naming either festival, health chiefs tasked with containing the virus have already begun tracing cases back to the Gran Canarian gay pride festival – attended by up to 80,000 people between May 5-15.
Meanwhile, three cases in Belgium have been linked with Darklands – a large-scale fetish festival in Antwerp, held from May 5-8. Organisers have since said there is ‘reason to assume’ someone at the event was infected.
Spanish health chiefs have also linked many cases to a single ‘sauna’ in Madrid.
At least 262 cases have been spotted worldwide.
It comes as the UK’s Department for Environment, Food & Rural Affairs (DEFRA) will this week warn of a potential risk of human to animal transmission.
Its guidelines will warn infected people to limit the risk of spreading the virus to cats, dogs, rabbits and rats.
There are also fears infected patients could contaminate their pet’s fur and allow it to be passed on to others in their household when petting.
The European Centre for Disease Prevention and Control (ECDC) this week warned monkeypox may become endemic to the continent, if transmission continues and it spreads to pets or wildlife.
Justine Shotton, president of the British Veterinary Association, said the association was monitoring the situation closely.
She believes the risk of infecting pets remains low but is ‘supportive of a cautious approach’ while officials seek to learn more about the virus.
Health chiefs have warned monkeypox, a virus endemic in parts of Africa and is known for its rare and unusual rashes, bumps and lesions, could also spread to some pets and become endemic in Europe. Undated handout file image issued by the UK Health Security Agency of the stages of Monkeypox
The smallpox vaccine, called Imvanex in the UK and Jynneos in the US, can protect against monkeypox because the viruses causing the illnesses are related
Ms Shotton said: ‘It would be a sensible decision to keep your distance from a pet while in quarantine.
‘If I was diagnosed with monkeypox I would do whatever I could to limit contact, such as asking a friend or relative to take care of it.’
She added: ‘There is currently no evidence of transmission between humans and cats and dogs but we know rabbits and rodents are susceptible.
‘If you have concerns about your pets health — if they have a fever, respiratory issues, poor appetite or lethargy — speak to a vet.
‘The chances are it will be something other than monkeypox but it’s worth getting it checked.’
Uk health teams are contacting high-risk contacts of confirmed cases and advising them to self-isolate at home for three weeks and avoid contact with children.
They are also being offered the smallpox Imvanex vaccine — which is around 85 per cent effective against monkeypox because the viruses are so similar — to form a buffer of immune people around a confirmed case to limit the spread of the disease.
The strategy, known as ring vaccination, has been used in previous monkeypox outbreaks and is also being carried out in some EU countries.
The Government has around 5,000 doses of the monkeypox vaccine has ordered 20,000 more doses.
Officials are confident the virus will not grow exponentially like Covid, although they are understood to be planning an online dashboard that tracks case numbers, which sparked controversy during the coronavirus pandemic.
People with unusual rashes or lesions, particularly if they have had a new sexual partner, have been urged to contact NHS 111 or their local sexual health clinic.
But health officials stressed people should phone ahead before attending in person.
Despite the rise in cases, the UKHSA said that the risk to the UK population ‘remains low’.
The health body said that a ‘notable proportion of the cases’ identified have been among people who are gay, bisexual and men who have sex with men.
These people in particularly have been urged to be aware of symptoms, particularly if they have recently had a new sexual partner.
