Description of the situation
On 15 June 2021, a third case of monkeypox was confirmed in the United Kingdom of Great Britain and Northern Ireland (for more information on the first two cases, kindly see the WHO Disease Outbreak News (DON) published on 11 June 2021). The case developed a vesicular rash on 13 June 2021. Swabs of the lesions were received for diagnostic confirmation on 14 June and orthopoxvirus was confirmed by polymerase chain reaction (PCR) on 15 June 2021.
This case is a family member of the two cases diagnosed in the United Kingdom in May 2021. All three cases were admitted to a specialist infectious diseases unit. They have now fully recovered and been discharged from hospital.
Public health response
The health authorities identified 30 close contacts of the cases and all have completed 21 days of active monitoring from their last date of exposure. No transmission outside the family has been identified.
The health care workers caring for the three cases within the specialist infectious diseases unit have been vaccinated.
Information about these three cases was shared with the Nigerian National IHR Focal Point who continue to gather further information regarding potential sources of infection and exposure in Nigeria. Active search has not yielded any cases related to the index case of this exportation. Animal health experts are collaborating in field activities to further explore potential sources of exposure.
WHO risk assessment
Monkeypox is a sylvatic zoonosis with incidental human infections that usually occur sporadically in forested parts of Central and West Africa. It is caused by the monkeypox virus and belongs to the Orthopoxvirus family. Monkeypox can be transmitted by contact and droplet exposure via exhaled large droplets. The incubation period of monkeypox is usually from 6 to 13 days but can range from 5 to 21 days. The disease is often self-limiting with symptoms usually resolving spontaneously within 14-21 days. Symptoms can be mild or severe, and lesions can be very itchy or painful. Milder cases of monkeypox may go unreported and represent a risk of person-to-person transmission. The animal reservoir remains unknown, although is likely to be among rodents. Contact with live and dead animals through hunting and consumption of wild game or bush meat are known risk factors.
There are two clades of monkeypox virus, the West African clade and Congo Basin (Central African) clade. Although the West African clade of monkeypox virus infection sometimes leads to severe illness in some individuals, disease is usually self-limiting. The case fatality ratio for the West African clade has been documented to be around 1%, whereas for the Congo Basin clade, it may be as high as 10%.
To date, in the United Kingdom, there have been only seven cases of monkeypox reported, these three cases, three previously imported cases from Nigeria – two in September 2018 and one in December 2019 and one case of nosocomial transmission in a health care worker in England in 2018 due to contact with contaminated bed linen.
As mentioned above, the third confirmed case is an extended close contact of the previous two cases and all cases are from the same household and have fully recovered. No additional contacts have been identified linked to this new case. None of the close contacts have travelled outside the United Kingdom following exposure. Therefore, this case does not change the public health risk in the country and the chance of further disease spread remains low. The possible source of exposure and risk of further spread in Nigeria is being assessed.
For background information on monkeypox outbreaks in Nigeria, kindly see the DON published previously on 11 June 2021.
WHO advice
Any illness during travel or upon return should be reported to a health professional, including information about all recent travel and immunization history. Residents and travelers to endemic countries, such as Nigeria, should avoid contact with sick, dead or live animals that could harbor monkeypox virus (rodents, marsupials, primates) and should refrain from eating or handling wild game (bush meat). The importance of hand hygiene using soap and water or alcohol-based sanitizer should be emphasized.
A patient with monkeypox should be isolated during the infectious period, i.e., during the rash stage of the illness, and contacts should be observed in quarantine. Timely contact tracing, surveillance measures and raising awareness of emerging diseases among health care providers are essential parts of preventing secondary cases and effective management of monkeypox outbreaks.
Health care workers caring for patients with suspected or confirmed monkeypox should implement standard contact and droplet infection control precautions. Samples taken from people and animals with suspected monkeypox virus infection should be handled by trained staff working in suitably-equipped laboratories.
WHO does not recommend any restriction for travel to, or trade with, United Kingdom of Great Britain and Northern Ireland or Nigeria based on available information at this time.
Further information
WHO factsheet on monkeypox, 9 December 2019
WHO monkeypox outbreak tool kit
WHO disease outbreak news, Monkeypox, Nigeria 11 June 2021
WHO disease outbreak news, monkeypox, Nigeria, 21 December 2017
Monkeypox: Introduction. Monkeypox online training module