UK health officials are preparing for any potential cases of a new strain of mpox after the World Health Organization declared outbreaks of the virus in Africa to be a global emergency. The strain, known as clade 1b, emerged in the Democratic Republic of the Congo last year. The UK Health Security Agency said there were no cases of the virus in the UK. Dr Meera Chand, a UKHSA deputy director, said: “The risk to the UK population is currently considered low. However, planning is under way to prepare for any cases that we might see in the UK. “This includes ensuring that clinicians are aware and able to recognise cases promptly, that rapid testing is available, and that protocols are developed for the safe clinical care of people who have the infection and the prevention of onward transmission.” Mpox, previously known as monkeypox, is passed on through close physical contact. The disease causes flu-like symptoms and pus-filled lesions, and is usually mild but can kill. Children, pregnant women and people with weakened immune systems are at higher risk of complications. The WHO director general, Dr Tedros Adhanom Ghebreyesus, declared the outbreak a public health emergency of international concern (PHEIC) under the international health regulations (2005) on Wednesday. The virus was previously declared a PHEIC in July 2022 but this was lifted in May 2023 after a global decline in cases. The clade 1b strain emerged last year, with 100 lab-confirmed cases also detected in countries that had not previously reported mpox – Burundi, Kenya, Rwanda and Uganda. Before spring 2022, cases in the UK were usually associated with travel to or from countries where mpox is endemic, particularly in west or central Africa. However, in May that year sustained transmission of the virus was identified in the UK, leading to a large outbreak, mostly in men who have sex with men. A UK vaccination programme was launched that summer and ended in July 2023. According to the UKHSA, there were 3,732 confirmed and highly probable mpox cases reported in the UK up to 31 December 2022. In 2023 and up to 31 July this year, 286 cases were reported. Of these, 269 were in England, with 116 patients presumed to have caught the virus in the UK and 82 outside the country.