The WHO confirmed that two cases of the recombinant strain, which combines genomic elements of monkeypox virus (MPXV) clades Ib and IIb, have been identified to date: one in the United Kingdom and one in India. Both patients had a recent travel history and neither experienced serious illness.
No secondary cases were detected after contact tracing.
The WHO has published a detailed update on the two cases and national responses.
Recombination is a natural process. That can occur when two related viruses infect the same person and exchange genetic material, producing a new variant.
According to the WHO, a detailed genomic analysis shows that the two individuals “fell ill several weeks apart with the same recombinant strain,” suggesting that there may be additional undetected cases.
What is mpox?
Mpox is an infectious disease caused by monkeypox virus (MPXV), part of the genus Orthopoxvirus, which also includes the virus that causes smallpox.
It spreads through close physical contact, including sexual contact, and in some cases through contaminated materials or respiratory droplets.
Symptoms usually include fever, swollen lymph nodes, and a rash and/or lesions.
Click here for the WHO fact sheet on mpox.
Two cases detected
He case in the UK It was detected in December 2025 in a traveler returning from a country in the Asia Pacific region. Initial laboratory testing identified the virus as clade Ib, but full genome sequencing later revealed that it contained genetic regions from clade Ib and clade IIb strains. Repeat sequencing confirmed the findings and demonstrated that the virus “can replicate and has potential for further transmission.”
in indiaone patient who developed symptoms in September 2025 was initially classified as infected with clade II MPXV. However, following updates to global genomic databases, the virus was reclassified as the same recombinant strain identified in the United Kingdom. The Indian case represents the earliest known detection of this strain.
“Due to the small number of cases found to date, conclusions regarding the transmissibility or clinical characterization of mpox due to recombinant strains would be premature and it remains essential to maintain vigilance on these developments”said the WHO.
The clinical presentations in both cases were consistent with known mox infections.
Risk assessment unchanged
WHO’s overall risk assessment remains unchanged: The risk is assessed as moderate for men who have sex with men with new or multiple partners and for sex workers or other people with multiple casual sexual partners, and low for the general population without specific risk factors.
At the same time, the WHO warned that clade differentiation PCR tests alone “may not reliably identify recombinant MPXV strains,” meaning genomic sequencing is essential for detection.
“All countries should remain alert to the possibility of MPXV genetic recombination,” the WHO said, urging continued epidemiological surveillance, sequencing, vaccination of at-risk groups and infection prevention and control measures.
The WHO warned that no travel or trade restrictions are justified based on current information.
