What we know about new Mpox strain after first case caught in UK

Independent

08-04-2025

Another case of the potentially serious mpox virus has been found in the north east of England, in what could be the first case of community transmission in the UK.
Britain's health security agency (UKHSA) said on Tuesday it has discovered the first confirmed human case of Clade Ib mpox in the country where the infected person has no reported travel history.
This suggests the person contracted the highly infectious virus from someone else in the UK.
What is special about this latest mpox case?
All previous cases in the UK have been found in people who have either travelled to an affected country or have a link to someone who has.
The UKHSA said more work is ongoing to determine where the individual may have caught the infection - which was discovered last month.
They said all contacts have been followed up and no further cases were identified.
The government agency was keen to stress that the risk to the UK population remains low.
What is mpox?
Common symptoms of mpox include a skin rash or pus-filled lesions which can last 2 to 4 weeks. It can also cause fever, headaches, muscle aches, back pain, low energy and swollen lymph nodes.
'Mpox is a disease caused by a virus known as monkeypox, which was first seen in the late 1950's in laboratory monkeys with a human case noted in 1970,' explains Dr Jon Roberts, professor of Health Protection at the University of the West of England. 'The virus is 'zoonotic' – meaning it can affect different animals, including humans, although cases in humans have been rare.'
Mpox spreads through close physical contact with an infected person.
'It spreads through skin-to-skin contact with rashes or blisters, touching their clothing, bedding or towels, or when they cough or sneeze near you,' explains Dr Kathryn Basford at ASDA Online Doctor. 'It can also be transmitted by infected animals through bites but this is less common in the UK.'
The virus commonly has two types or 'clades' which present with differing clinical severity if seen in humans.
'Clade I can be associated with more severe disease and in the UK is currently designated a high consequence infectious disease (HCID),' highlights Roberts. 'Clade II is no longer designated a HCID and was associated with a global outbreak of infection in 2022-2023, including cases in the UK.'
The disease stopped being classified as a high consequence infectious disease (HCID) last month, after a review of criteria including mortality rate and available interventions.
Further information about symptoms is available on the NHS website.
What are scientists saying about the latest development?
UKHSA Mpox Incident Director Dr Gillian Armstrong said: 'The risk to the UK population from mpox remains low.
'The majority of people who have presented with symptoms report close physical contact, including massages, or sex prior to developing symptoms.
'Regardless of whether you have travelled or not, it is important to remain alert to the risks. Anyone who thinks they may have mpox should contact NHS 111 for advice on what to do.
'While mpox infection is mild for many, it can be severe for some and UKHSA is committed to preventing its spread within the UK.'
The history of mpox
Mpox was first discovered in 1958 when outbreaks of a pox-like disease occurred in monkeys kept for research. The first human case was recorded in 1970 in the Democratic Republic of the Congo (DRC), and since then the infection has been reported in a number of African countries.
Prior to 2022 most cases were reported from the DRC and Nigeria.
In October, England confirmed its first case of clade Ib mpox, a different strain from the one circulating at low levels in the UK since 2022.
A month before this, the government announced the purchase of additional mpox vaccine doses to strengthen the country's defences against the virus.