CDC concerned about possibility of undetected spread of monkeypox in UK

JThe Centers for Disease Control and Prevention expressed concern over an unusual outbreak of monkeypox in the UK on Tuesday, suggesting there appears to be at least undetected transmission of the virus and warning of the possibility of the outbreak spreading beyond UK borders.

“We are concerned that this is very different from what we generally think of monkeypox. And I think we are concerned that it could spread outside the UK associated with this,” said Jennifer McQuiston, a senior official at the CDC, to STAT in an interview.

Seven confirmed cases and one probable case of monkeypox have been discovered in the UK since the start of May – an unusually high number given that human cases of monkeypox are rare and particularly rare outside 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 the nationally infected people have a known link to the traveler and the timing of the cases suggests he was not the source of these infections.


What complicates the situation – and amplifies the concern – is the fact that the other cases comprise two distinct groups that have no discernible connection to each other. Two of the confirmed cases and the only probable case are a family unit, World Health Organization expert Maria Van Kerkhove told a news conference on Tuesday. The other four confirmed cases, most recently disclosed, have been identified by the UK Health Security Agency as gay, bisexual or other men who have sex with men – three from London and a fourth from Newcastle, nearly 300 miles north. north. All four were likely infected in London, the agency said.

It is not known how any of these people contracted the virus. Transmission is thought to occur primarily through virus-containing droplets, but direct contact with lesions or bodily fluids of an infected person, or indirect contact via contaminated clothing or linens, can also lead to 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 may contain additional cases that have yet to be detected. Van Kerkhove, who heads the emerging diseases and zoonoses unit of the WHO’s health emergencies programme, said sequencing of the virus is underway in the UK to try to determine if the cases are genetically linked.

There is no suggestion that monkeypox is spreading to large numbers of people in the UK. Yet evidence that there are likely undetected cases is fueling concern about the extent of transmission and whether the virus has traveled further.

“You have two clusters that have no connection to travel or other people known to be associated with a recognized outbreak. This suggests there are unknown chains of transmission,” McQuiston said. “If there appear to be unknown chains of transmission, that just puts us on alert to think: could this spread outside of the UK?”

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

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

There are no drugs or vaccines specific to monkeypox, but the smallpox vaccine has been used in the past to help stop the transmission of monkeypox, such as in a 2003 outbreak in the United States dating back to imported exotic animals. During this outbreak, 71 people in six states contracted monkeypox.

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

Due to cases being found among gay, bisexual or other men who have sex with men, public health authorities in the UK have alerted sexual health clinics to be on the lookout. watch out for people with unexplained rashes. McQuiston said the CDC is considering issuing a health alert to medical professionals and sexually transmitted infection clinics in this country.

“There is a lot of travel between the UK and the US and other parts of the world. So 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 messages to our STI clinics…about what to watch out for, what to be vigilant about,” she said.

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

Communications around the outbreak must be crafted carefully, McQuiston said.

“This is certainly a population that has been stigmatized for sexually transmitted infections like HIV in the past. And I think we learned a bit from those experiences about how to approach that with the kind of sensitivity that it requires,” she said.

Public health investigators in the UK are working to trace who confirmed cases were in contact with before falling ill, to try to find the source of their infections. But they are also looking to identify contacts of infected people to see if they have transmitted the virus to others.

McQuiston said that to date the CDC has not been informed that any Americans have come forward on the UKHSA contact list for these cases. But she revealed six people in the US were being watched because they were on the same flight as the man who traveled from Nigeria to the UK on May 4. Although there was no suggestion the individuals 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 outbreak in the UK is a reminder of the need to pay more attention to monkeypox, whose disease dynamics are poorly understood, said Ibrahima Socé Fall, WHO’s deputy director-general for emergency response.

“Clearly the main issue we need to investigate is really knowing the true extent of monkeypox transmission in Africa and making sure that we invest in prevention and treatment tools for those most at risk in Africa. Africa,” he said.

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