The CDC in the United States has expressed concern about the outbreak of unusual monkeypox outbreaks in the United Kingdom

The US Centers for Disease Control and Prevention (CDC) on Tuesday expressed concern about an unusual monkeypox outbreak in britain, arguing that there appeared to be at least some undetected spread of the virus there, and warned of the possibility of the outbreak spreading outside the UK.

"We do have a certain level of concern, which is very different from what we usually think of as monkeypox." I think we have some concerns that this could spread outside the UK," Jennifer McQuiston, a senior cdc official, told STAT in an interview.

Since the beginning of May, 7 confirmed cases and 1 suspected case of monkeypox have been detected in the UK. Cases of monkeypox in humans are uncommon and are particularly rare outside West and Central Africa. While one of the cases recently traveled to Monkeypox-endemic Nigeria, the others appear to have contracted in the UK. None of the people infected in the UK had any known link to the traveller, and the onset of the disease indicated that he was not the source of these infections.

Complicating the situation is that other cases are made up of two different groups with no apparent link to each other, which also exacerbates concerns. World Health Organization expert Maria Van Kerkhove said at a news conference Tuesday that two of the confirmed cases and one possible case were a family unit. Four other recently disclosed confirmed cases were identified by the Health Security Agency as gay, bisexual or other men who had sex with men – three from London and the fourth from Newcastle, nearly 300 miles north. The agency said all four people could have been infected in London.

It is not known how any of these people contracted the virus. Transmission is thought to occur primarily through droplets carrying the virus, but direct contact with a lesion or body fluid in an infected person, or indirect contact through contaminated clothing or bed sheets, may also lead to transmission.

The fact that there are two distinctly unrelated clusters suggests that there may be more than one chain of transmission in the country, each of which may contain additional cases that have not yet been detected. Van Kerkhove, who leads the unit on emerging diseases and zoonotic diseases in WHO's health emergency plan, said the UK was undergoing virus sequencing to try to determine if there was a genetic link in these cases.

There is no indication that monkeypox is spreading to large numbers of people in the UK. However, there is evidence that there may be some undiscovered cases, which adds to concerns about how much transmission may be there and whether the virus has spread farther afield.

"You have two clusters and no contact with travel or other people who are known to be associated with a recognized outbreak. This suggests that there is an unknown chain of transmission occurring," McQuiston said. "If there's an unknown chain of transmission, it just makes us vigilant and thinking. Will this spread outside the UK? ”

While human monkeypox cases outside Africa are rare, some cases have been exported in recent years to the United States (two in 2021), the United Kingdom, Israel and Singapore. The UK Health Service said the last four cases were infections with the West African monkeypox branch, which caused less disease than the Central African branch.

Symptoms of monkeypox are similar to smallpox but milder than smallpox, and the World Health Organization declared success in eliminating smallpox in 1980. In addition to flu-like symptoms, infection can trigger a unique rash. Many diseases can cause rashes, but monkeypox rashes have some unusual features, especially blisters that form on the palms of the hands.

One vaccine, which was licensed in the United States in 2019, is for people aged 18 and older to prevent smallpox and monkeypox, namely Jynneos of Bavarian Nordic. A second vaccine, ACAM2000 from Emerald Product Development, protects against smallpox and is thought to provide some protection against monkeypox. But both vaccines are licensed only for people who are considered to be at high risk of contracting the disease. In a 2003 outbreak in the United States involving 47 people, the smallpox vaccine was used.

In Africa, about one in ten monkeypox cases are fatal, and children are more likely to have severe illness and death.

As cases have been detected in people who have lesbian, gay, bisexual or other men who have sex with men, public health in the UK has alerted sexual health clinics to people with unexplained rashes. McQuiston said the CDC is considering sending health alerts to the nation's healthcare industry and STIs clinics.

"There's a lot of travel between the UK and the US and other parts of the globe. So I think our concern is that given that you do have four cases of men who have sex with men, we may need to consider sending a message to our STIs clinic... About what to watch out for, what to be wary of," she said.

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

McQuiston said communications around the outbreak must be carefully crafted. "This is certainly a group of people who have been stigmatized in the past for sexually transmitted infections such as HIV." "I think we've learned something from these experiences about how to approach this with the required sensitivity," she said. ”

Public health investigators in the UK are working to trace who these confirmed cases were in contact with before becoming ill in an attempt to find the source of their infection. But they are also seeking to identify contacts of infected people to find out if they have spread the virus to others.

So far, McQuiston said, the CDC has not been informed that any Americans have appeared on the CONTACT LIST for these cases at the UKHSA. But she did reveal that six people in the U.S. were being monitored because they were on the same flight as the man who traveled from Nigeria to the United Kingdom on May 4. While there was no indication that the men had direct contact with the man — they sat within a three-row radius of his seat — the six men would be monitored for 21 days, she said.

Ibrahima Socé Fall, WHO Assistant Director-General for Emergency Response, said the outbreak in the UK was a reminder that we needed to pay more attention to monkeypox, which knew very little about its disease dynamics.

"Obviously, the main issue we need to investigate is to really understand the true extent to which monkeypox is spreading in Africa and to ensure that we invest in prevention and treatment tools to help the people who are most exposed in Africa," he said. ”