GlobalHealth Threats

WHO has reported two cases of mpox due to a strain that contains genetic material from both clade Ib and clade IIb. These cases were identified in the United Kingdom and India. Both individuals had recent travel histories—one to a country in the Asia‑Pacific region, and the other to a country in the Arabian Peninsula where he works as an overseas employee. Both experienced only mild illness, and no additional infections were detected through contact tracing. WHO states "This information has two important implications: i) the origin of the recombinant strain remains unknown; and ii) transmission of this recombinant virus already involves at least four countries in three WHO regions, and is therefore likely to be more widespread than currently documented."

In the United Kingdom, the case was detected in December 2025. Initial laboratory testing classified the infection as clade Ib. Further testing revealed genetic elements from both clade Ib and clade IIb, and confirmed it is capable of replication and has the potential for onward transmission.

In India, a patient who developed symptoms in September 2025 was initially identified as infected with a clade II strain. After genetic information was published publicly, in December, it was noted to be the same recombinant variant detected in the UK, making the Indian case the earliest known occurrence of this strain.

WHO emphasised that “Due to the small number of cases found to date, conclusions about transmissibility or clinical characterization of mpox due to recombinant strains would be premature, and it remains essential to maintain vigilance regarding this development."

The report further stated that "the overall WHO public health risk assessment for mpox remains unchanged: the risk is assessed as moderate for men who have sex with men with new and/or multiple partners and for sex workers or others with multiple casual sexual partners, and low for the general population without specific risk factors."