Health experts are advising the public to be extra cautious following an increase in cases of an infectious illness in the UK. Recent data reveals that there have been 16 confirmed instances of a particular strain of mpox in England.
According to Travel Health Pro, as of September 11, 2025, a total of 16 cases of clade Ib mpox have been identified in the UK, all of which are in England. Many of these cases have connections to travel to regions where mpox clade Ib is prevalent.
This variant is thought to be more transmissible than the clade II strain that caused an outbreak in the UK in 2022. Mpox, previously known as monkeypox, can spread from person to person through close contact with mpox blisters or scabs.
Symptoms of mpox typically appear between five and 21 days after exposure. Initial signs may include high fever, severe headaches, muscle pain, backache, swollen glands, chills, fatigue, and joint pain. A rash may develop on the body within one to five days after the onset of symptoms.
The World Health Organization (WHO) warns that young children, pregnant women, and individuals with weakened immune systems, particularly those with poorly managed HIV, are at higher risk of severe complications from mpox, which can be fatal. However, most individuals recover within four weeks.
The UK Health Security Agency (UKHSA) has confirmed that all 16 cases in the UK were located in England, with most cases linked to travel to areas where mpox clade Ib is circulating.
Since 2024, several African countries have been dealing with an increase in clade Ib mpox cases. Additionally, imported cases have been reported in various countries, including Belgium, Canada, France, Germany, Sweden, and the United States.
The NHS advises individuals to contact 111 if they exhibit mpox symptoms and have recently visited central or east Africa and been in close contact with someone showing signs of mpox.
While the illness is considered rare, there are preventative measures individuals can take to lower their risk of contracting and transmitting the disease. These precautions include:
From 2023 to 2025, the UKHSA recorded a total of 589 cases of mpox clade IIb in the UK. The UKHSA mentioned that despite ongoing imports of mpox clade IIb, case numbers have likely remained lower than those in 2022 due to the high levels of vaccine protection suppressing transmission.