CDC concerned about possible undetected spread of monkeypox in UK


CDC concerned about possible undetected spread of monkeypox in UK

TThe Centers for Disease Control and Prevention on Tuesday expressed concern over an unusual outbreak of monkeypox in the UK, suggesting there appears to be at least one undetected transmission of the virus there, and warned of the possibility that the Outbreak could spread beyond UK borders.

“We have a level of concern that this is very different than what we normally think of monkeypox. And I think we have some concerns that this could spread outside of the UK,” Jennifer McQuiston, a senior CDC official, said in an interview with STAT.

Since the beginning of May, seven confirmed and one probable case of monkeypox have been detected in the UK – an unusually high number considering human cases of monkeypox are uncommon and particularly rare outside of West and Central Africa. While one of the cases had recently traveled to Nigeria, where monkeypox is endemic, the others appear to have contracted the virus in the UK. None of those infected domestically have any known links with the traveler, and the timing of the cases’ onset suggests he was not the source of these infections.


Complicating the situation – and heightening concern – is the fact that the other cases are about two distinct groups with no discernible links to one another. Two of the confirmed cases and the only probable case are a family unit, Maria Van Kerkhove, an expert with the World Health Organization, said at a news conference on Tuesday. The other four confirmed cases most recently known have been identified by Britain’s Health Security Agency as gay, bisexual or other men who have sex with men – three from London and a fourth from Newcastle, almost 300 miles north. All four were probably infected in London, the authority said.

It is not known how any of these people contracted the virus. Transmission is thought to occur primarily through virus-laced droplets, but direct contact with lesions or bodily fluids of an infected person, or indirect contact through contaminated clothing or bedding can also result in transmission.


The fact that there are two seemingly unconnected clusters suggests there may be more than one chain of transmission in the country, each of which could contain additional cases that have not yet been detected. Van Kerkhove, who heads the unit for emerging diseases and zoonoses in WHO’s health emergencies programme, said virus sequencing was underway in the UK to see if the cases were genetically linked.

There is no evidence that monkeypox is spreading to large numbers of people in the UK. Still, the evidence that there are likely some undetected cases is stoking concerns about how many transmissions there might be and whether the virus has traveled further.

“You have two clusters that have no connection to travel or anyone else known to be linked to any recognized outbreak. It suggests there are unknown chains of transmission,” McQuiston said. “If it appears that there are unknown chains of transmission, that only makes us vigilant as we consider: Could this be spreading outside the UK?”

Although human monkeypox cases are rare outside of Africa, in recent years there has been a spate of cases exported to the United States (two in 2021), the United Kingdom, Israel and Singapore. The four most recent cases were infected with the West African group of monkeypox, which causes milder disease than the Central African group, the UKHSA said.

Monkeypox has similar but milder symptoms than smallpox, which was declared eradicated in 1980. In addition to flu-like symptoms, infection triggers a characteristic skin rash. Many conditions can cause rashes, but monkeypox rash has some unusual features, most notably the fact that blisters can form on the palms of the hands.

There are no monkeypox-specific drugs or vaccines, but the smallpox vaccine has been used to stop transmission of monkeypox in the past, such as during a 2003 outbreak in the United States that was traced to imported exotic animals. In that outbreak, 71 people in six states contracted monkeypox.

In Africa, monkeypox is fatal in about 1 in 10 cases, with severe illness and death being more likely in children.

Due to the discovery of cases in gay, bisexual and other men who have sex with men, health authorities in the UK have told sexual health clinics to be on the lookout for people with unexplained skin rashes. McQuiston said the CDC is considering sending a health alert to medical professionals and sexually transmitted infection clinics in that country.

“There is a lot of travel between the UK and the US and other global areas. I think our concern is that given that you have four cases among men who have sex with men, we probably need to think about sending our STI clinics a message … about what to look out for, what to look out for need to be vigilant,” she said.

Van Kerkhove said the WHO has reached out to European countries through its Copenhagen-based European office to raise awareness about the risk of finding cases of monkeypox.

Communications surrounding the outbreak must be designed with care, McQuiston said.

“This is certainly a demographic that has historically been stigmatized for sexually transmitted infections such as HIV. And I think we’ve learned a little bit from those experiences how to approach this with the kind of sensitivity that it requires,” she said.

Public health investigators in the UK are working to find out who the confirmed cases were in contact with before they fell ill to try to find the source of their infections. But they are also trying to identify contacts of those infected to see if they have passed the virus on to others.

McQuiston said the CDC has not yet been informed that Americans have appeared on the UKHSA’s contact list for these cases. However, she revealed six people are under surveillance in the United States because they were on the same flight as the man who traveled from Nigeria to the UK on May 4. Although there is no indication the people had direct contact with the man – they sat within three rows of his seat – the six people will be monitored for 21 days, she said.

The UK outbreak is a reminder of the need to pay more attention to monkeypox, whose disease dynamics are poorly understood, said Ibrahima Socé Fall, WHO deputy director-general for emergency response.

“Clearly, the key issue we need to investigate is really knowing the real extent of monkeypox transmission in Africa and making sure we invest in tools to prevent and treat people who are most at risk in Africa,” he said he.

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