The person was sick when they boarded the plane. Five days before leaving Nigeria for Britain, they noticed a rash that spread into a scattering of fluid-filled bumps. When the plane touched down on 4 May, they wasted no time. The person attended hospital where doctors, alerted by their recent travel, immediately suspected monkeypox. The patient was isolated and a doctor, clad in full PPE, took a swab from a blister on their skin.
Because monkeypox is listed as a “high-consequence infectious disease”, the situation moved fast. The sample was sent to Porton Down science park in Wiltshire where the UK Health Security Agency’s rare and imported pathogens laboratory swiftly ran a PCR test. This confirmed the infection, which the agency announced the next day, on 7 May.
Sporadic cases of monkeypox are rare, but not new in Britain. In total, seven cases have been recorded, in 2018, 2019 and 2021, all linked to travel to Nigeria where monkeypox is endemic.
But as public health officials were soon to discover, this year was to be different. For the first time, doctors have uncovered chains of transmission in the community – not only in Britain – among people with no known links to travel. The UK has confirmed 20 cases, but more than 100 known or suspected cases are under investigation in the US, Canada, France, Germany, Belgium, Spain, Portugal, Italy, Sweden and Australia.
“It’s come into the UK, it’s come into other countries, and now we have to deal with it and figure out what’s going on,” said Prof David Heymann, distinguished fellow at the Chatham House global health programme and former executive director of the communicable diseases cluster for the World Health Organization.
Monkeypox is a viral infection that most people shrug off. There are two forms. The more serious is the central African or Congo strain. The latest cases involve the milder west Africa strain. Data from Africa suggest about 1% of people with cases die. The concern is less around the impact on healthy people, but on the vulnerable – those with weakened immune systems, for example – and on the virus spreading in healthcare settings.
Despite its name – the virus was first detected in macaques – most human cases of monkeypox are believed to come from contact with other infected animals, such as rodents. Historically, transmission between humans has been limited – infections sometimes spread in homes but soon fizzle out.
The virus spreads through large respiratory droplets, calling for prolonged or frequent face-to-face contact, or contact with body fluids such as saliva, or skin lesions, either directly or through contaminated sheets, towels and other items.
A week after confirming the first patient, the UKHSA reported two more in a family in London, with no links to the first case. The announcement on Saturday 14 May was “crucial” according to one doctor, because it carried images of monkeypox lesions. These were seen by specialists struggling to diagnose patients with unexplained rashes at sexual health clinics. They immediately sent swabs to Porton Down, which confirmed the cases as monkeypox. On the Monday, the health agency confirmed four more cases, all men who have sex with men and appeared to have caught the virus in London.
The increase in mostly unrelated cases prompted the UK’s chief medical officers to send immediate advice to healthcare workers via the NHS central alerting system. It called on providers to ensure they had sufficient PPE to assess and treat patients and noted that the smallpox vaccine, Imvanex, offered some protection against monkeypox if given soon after exposure. The vaccine is already being offered to healthcare workers and contacts of cases at high risk of infection, and the Department of Health has secured thousands of doses in case the outbreak grows.
The alert put the spotlight on men who have sex with men (MSM), and a flurry of cases have since been confirmed, pointing to spread in sexual networks. While public health experts rush to contain the outbreak, they warn against focusing on any particular group. “This could easily have popped up in a different context,” said one senior specialist in sexual health. “The MSM phenomena may well have been a very quick way to have drawn our attention to there being skin-to-skin transmission in the community.”
Sir Ali Zumla, professor of infectious diseases and international health at University College London, said focusing on men who have sex with men was “prejudicial, unfair and stigmatising”, adding that clusters of monkeypox would occur in any group in close contact with infected people. It was “highly unlikely” that the clusters were due to any change in the virus, he added.
Dr Meera Chand, director of clinical and emerging infections at the UKHSA, said “everyone” should be alert to monkeypox symptoms. “If you notice any unusual rashes or lesions consistent with monkeypox, please contact NHS 111 or a sexual health service, calling ahead before your visit. A notable proportion of recent cases in the UK and Europe have been found in gay and bisexual men, which is why we are particularly encouraging them to be alert to the symptoms. We are working to trace contacts of cases and offering vaccination where appropriate, and meanwhile we are rapidly investigating how the virus is transmitting to understand why we are seeing this unusual outbreak.”