The World Health Organization (WHO) has confirmed the detection of a novel recombinant monkeypox (mpox) virus in two separate patients—one in the United Kingdom and another in India. Both cases were identified through whole‑genome sequencing that revealed a virus combining genetic elements of clade Ib and clade IIb. While neither patient suffered severe illness and no secondary transmissions have been recorded, WHO says the findings underscore the need for ongoing genomic surveillance of mpox worldwide.
Mpox, caused by the monkeypox virus (MPXV) of the Orthopoxvirus genus, spreads primarily through close physical contact, including sexual activity, and can also be transmitted via contaminated materials or respiratory droplets. Typical symptoms include fever, swollen lymph nodes, and a characteristic rash or skin lesions. The disease has been monitored globally since a multi‑country outbreak began in 2022, prompting heightened public‑health vigilance.
The first recombinant case was detected in December 2025 in the United Kingdom. The patient had recently returned from a country in the Asia‑Pacific region. Initial laboratory testing classified the virus as clade Ib, but subsequent whole‑genome sequencing revealed the presence of genetic regions from both clade Ib and clade IIb. The second case, identified retrospectively from a September 2025 sample in India, involved a traveler who had been in a country on the Arabian Peninsula. Genomic analysis showed the same Ib/IIb recombinant profile, suggesting that the two infections were caused by the same newly emerged strain.
Both individuals experienced clinical presentations consistent with other mpox clades and recovered without severe complications. Comprehensive contact tracing in the United Kingdom and India found no secondary cases, and WHO’s risk assessment for the global population remains unchanged.
What makes a recombinant mpox strain?
Recombination is a natural process that can occur when a single host is infected simultaneously with two related viral strains. The viruses exchange genetic material, producing a hybrid that may carry traits from each parent. In the current cases, the recombinant virus blends genomic segments of clade Ib—historically associated with milder disease in West Africa—and clade IIb, which was predominant in the 2022 outbreak. WHO’s disease‑outbreak‑news release explains that “detailed genomic analysis shows the two individuals fell ill several weeks apart with the same recombinant strain, suggesting that additional undetected cases may exist” (WHO DON 595).
WHO’s risk assessment and public‑health guidance
Despite the emergence of this recombinant virus, WHO maintains that the overall public‑health risk remains moderate for men who have sex with men (MSM) who have new or multiple partners, as well as for sex workers or others with multiple casual sexual partners. For the general population without specific risk factors, the risk is assessed as low. WHO urges countries to sustain “enhanced genomic surveillance, rapid case detection, and thorough contact tracing” to monitor any further spread (WHO mpox factsheet).
Why continued monitoring matters
Recombinant viruses can, in theory, acquire new characteristics that affect transmissibility, disease severity, or vaccine effectiveness. While no such changes have been observed in the two reported cases, the possibility of undetected transmission underscores the importance of sequencing every confirmed mpox infection. WHO’s statement emphasizes that “the detection of a newly identified recombinant mpox virus … underscores the need for continued genomic surveillance.”
Health authorities in both the United Kingdom and India have completed contact‑tracing investigations and reported no onward transmission. Nonetheless, the fact that the two cases occurred in different continents and were linked by travel histories highlights the potential for international spread of novel variants, especially in a globally mobile population.
Practical steps for clinicians and the public
Clinicians are advised to consider mpox in patients presenting with fever, lymphadenopathy, and rash, particularly if the patient reports recent travel or close contact with a known case. Laboratory confirmation should include PCR testing followed by whole‑genome sequencing when feasible, to identify any recombinant signatures.
The public is encouraged to remain vigilant for typical mpox symptoms, practice safe sexual behaviors, and seek medical evaluation promptly if symptoms arise. WHO continues to recommend that individuals at higher risk—such as MSM with multiple partners—stay informed about local guidance and consider vaccination where available.
Next steps and where to uncover updates
WHO will provide further updates as additional genomic data become available and as national health agencies report any new cases. The organization’s mpox situation page and disease‑outbreak‑news feeds will be the primary sources for official information. Health ministries in the United Kingdom and India have pledged to maintain robust surveillance and to share sequencing results with the global community.
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