WHO says monkeypox ‘could have been spreading undetected for years’

About 550 confirmed cases of monkeypox have been reported across 30 countries

Test tubes labelled "Monkeypox virus positive and negative". Reuters

Monkeypox could have been spreading for “months or possibly a couple of years” before it was detected in the latest outbreak, the World Health Organisation has said.

About 550 cases have been reported in the latest surge across 30 countries where the virus is not commonly found.

The WHO said one theory behind the latest outbreak could be that there is waning immunity to smallpox — which is from the same virus family as monkeypox — among adults under the age of 50.

Vaccines for smallpox are being offered to close contacts of diagnosed cases in this outbreak but they have not been routinely administered since about the time of the eradication of the disease in 1980.

That could mean that younger people who did not get the smallpox vaccine do not have protection, WHO experts suggested.

So far, 190 cases have been identified in the UK.

The UK Health Security Agency said that 86 per cent of England’s cases were London residents and only two were women.

Most (87 per cent) monkeypox cases have occurred in people aged between 20 and 49 years old.

And 111 cases are known to be gay, bisexual, or other men who have sex with men.

About 18 per cent of patients reported that they had travelled to different countries in Europe within 21 days of their symptoms starting.

“Investigations to date have identified links to gay bars, saunas and the use of dating apps in the UK and abroad," the UK agency said.

“Investigations continue but currently no single factor or exposure that links the cases has been identified.”

Dr Tedros Adhanom Ghebreyesus, Director General of the WHO, said: “Investigations are ongoing, but the sudden appearance of monkeypox in many countries at the same time suggests there may have been undetected transmission for some time.

“WHO is urging affected countries to widen their surveillance, to look for cases in the broader community.

“Anyone can be infected with monkeypox if they have close physical contact with someone else who is infected.

“The situation is evolving and we expect that more cases will continue to be found.

“It’s important to remember that generally, monkeypox symptoms resolve on their own, but it can be severe in some cases.”

The WHO’s monkeypox expert, Dr Rosamund Lewis, said: “Right now this is an outbreak and outbreaks can be stopped.

“So our efforts right now is to stop forward transmission of this outbreak and also to support the countries in Africa that live with this disease day in and day out.”

“The fact that this virus has appeared in Europe in a large number of cases, an increasing number of cases, is clearly cause for some concern, and it does suggest that there may have been undetected transmission for a while.

“What we don’t know is how long that may have been; we don’t know if it’s weeks, months or possibly a couple of years.

“It really is something that needs to be ascertained through deeper investigation of the initial cases that were reported and outbreak investigation of the clusters from which these cases arose.

“So we don’t really know whether it’s too late to contain. What WHO and all member states are certainly trying to do is to prevent onward spread.”

No deaths have been reported in the latest outbreak, but experts say that in countries where the virus is endemic, deaths are reported every year.

“One of the theories of course is that vaccination against smallpox was stopped in 1980 when smallpox was eradicated worldwide," Dr Lewis said.

“And so the collective immunity in the human population is not what it was at the time of smallpox eradication.

“So collectively, anyone under the age of 40, or 50, depending on which country you were born in, or where you might have received your vaccine against smallpox, would not now have that protection from that particular vaccine.

“Monkeypox is related to smallpox in the sense that the viruses are from the same family.”

Dr Meera Chand, director of clinical and emerging infections at the UK health agency, said: “We are working to break chains of transmission, including by contact tracing and vaccination.

“We are grateful to everyone who has come forward for testing and it is extremely important that everyone continues to be aware of the symptoms and to seek advice if they have concerns.

“We are reminding people to look out for new spots, ulcers or blisters on any part of their body.

“If anyone suspects they might have monkeypox, particularly if they have recently had a new sexual partner, they should limit their contact with others and contact NHS 111 or their local sexual health service as soon as possible, though please phone ahead before attending in person.”

The agency said it was working with venue owners and event organisers in London for “outreach activity”.