Chinese health authorities said on Thursday they had detected the new mutated mpox strain clade Ib as the viral infection spreads to more countries after the World Health Organization declared a global public health emergency last year. China's Centre for Disease Control and Prevention said it had found a cluster outbreak of the Ib subclade that started with the infection a foreigner who has a history of travel and residence in the Democratic Republic of the Congo. Four further cases have been found in people infected after close contact with the foreigner.