April 7, 2025

expert reaction to a case of Clade Ib mpox in an individual in the UK with no known travel history or links to previously confirmed cases

Scientists comment on a case of Clade 1b Mpox in an individual with no links to other cases, as confirmed by the UK Health Security Agency (UKHSA). 

Dr Jonas Albarnaz, Institute Fellow, Capripoxvirus Biology, The Pirbright Institute, said:

“Mpox presents as a skin rash with lesions (blisters) in any part of the body, including the palms of the hands, soles of the feet, mouth, genitals, and anus. Mpox rash can be confused with chickenpox. The mode of transmission of mpox is via close contact, and sustained human-to-human transmission has driven the current outbreak of clade 1b mpox in DRC and other countries in Central Africa, as well as the cases imported into countries outside Africa. So far, the clade 1b cases in the UK have been in individuals with recent travel history to Africa and their household contacts. The detection of a clade 1b case in a person without travel history or contact with the other clade 1b cases is surprising. Public health authorities should investigate how this recent case was acquired, but it’s likely that it was acquired from another infected person, via direct contact either with skin lesions or with contaminated surfaces or objects.

“Transmission of mpox from an asymptomatic person has been reported, but there’s limited information about the role of asymptomatic transmission in driving mpox outbreaks. Zoonotic transmission (animal to human) of mpox also occurs in endemic countries in Africa, but this is an extremely unlikely scenario given the absence of an animal reservoir in the UK.

“Vaccination remains the best strategy to prevent mpox and is recommended to individuals at higher risk of infection, which include contacts of mpox cases, healthcare workers, and people with multiple sexual partners. Two vaccines are approved against mpox: MVA-BN and LC16. These vaccines are based on weakened versions of a related orthopoxvirus (vaccinia) and were developed against smallpox. However, availability of these vaccines is very limited globally, representing a major bottleneck for the control strategies. It’s up to health authorities to decide on the most efficient strategy to deploy the available vaccine stocks. Ring vaccination, vaccination of close contacts of an infected person, is a common strategy to stop the chain of transmission of the pathogen infection.”

https://www.gov.uk/government/news/ukhsa-detects-first-case-of-clade-ib-mpox

Declared interests

Dr Jonas Albarnaz “No conflicts of interest to declare”