WHO Warns That New Recombinant Strains of Mpox Involving Clade Ib and IIb Emerging Globally
Nikhil Prasad Fact checked by:Thailand Medical News Team Feb 18, 2026 2 hours, 43 minutes ago
Medical News: Recombinant Mpox Detected Across Multiple Regions
The World Health Organization has issued a significant global alert after confirming the emergence of new recombinant strains of the mpox virus containing genetic material from both clade Ib and clade IIb lineages. These hybrid strains were identified through genomic sequencing in two separate patients linked to travel across Asia, the Arabian Peninsula, and Europe, raising concerns about wider, undetected international circulation. Viral recombination occurs when two related virus strains infect the same host and exchange genetic material, creating a new variant with combined genomic features. Although only two confirmed cases have been identified so far, such incidences could be far more prevalent and scientists warn that such recombination events demonstrate ongoing viral evolution and underscore the need for enhanced genomic monitoring worldwide.
Newly discovered recombinant mpox strains show hybrid genetic patterns spreading across continents
UK Case Reveals Hybrid Genome with Transmission Potential
The first identified recombinant strain was detected in the United Kingdom in October 2025, after a traveler returned from a Southeast Asian country famous for its tourism and sex industry, and developed mpox symptoms. Initial PCR testing classified the infection as clade Ib. However, whole genome sequencing revealed a mosaic viral genome containing segments from both clade Ib and clade IIb. Repeat sequencing of multiple samples, including clinical swabs and cultured virus isolates, confirmed identical recombinant genetic patterns, proving that the virus was viable and capable of replication. This
Medical News report highlights that laboratory analysis confirmed the recombinant strain’s authenticity, ruling out laboratory contamination or sequencing error. Contact tracing by the UK Health Security Agency found no secondary transmission, and all exposed healthcare workers had used protective equipment. The infected patient experienced typical mpox symptoms without severe complications.
India Case Predated UK Detection and Showed Nearly Identical Virus
Retrospective genomic analysis later revealed that an earlier case in India in September 2025 involved the same recombinant virus. The infected individual, an overseas worker returning from the Arabian Peninsula, initially tested positive for mpox through PCR testing, and early sequencing suggested clade IIb infection.
However, after updates to international genomic databases, scientists reclassified the virus as the same recombinant strain seen in the United Kingdom. Detailed sequencing showed more than 99.9 percent similarity between the two viruses, confirming a shared evolutionary origin. Researchers identified 34 recombinant genomic segments in the Indian strain and 28 in the UK strain, with 16 shared recombination regions. This finding suggests the recombinant strain was already circulating internationally months before its official discovery.
Genomic Evidence Demonstrates Complex Viral Evolution
Mpox belongs to the Orthopoxvirus genus, which includes the smallpox virus, and has historically been divided into cla
de I and clade II groups, each with different geographic origins and epidemiological characteristics. Recombinant strains combining clade Ib and IIb genetic material represent a significant evolutionary development. Importantly, scientists noted that PCR testing alone may fail to identify such recombinants, making genomic sequencing essential for accurate detection. Clinical symptoms in both confirmed recombinant cases resembled typical mpox infection, including fever, rash, and lymph node swelling, and neither patient experienced severe disease or required intensive medical intervention.
Public Health Response and Surveillance Intensified
Global health authorities are expanding surveillance and sequencing efforts to track emerging variants. Agencies including the National Health Service England and national public health laboratories have intensified diagnostic screening and genomic analysis. The WHO is coordinating vaccine access, strengthening laboratory networks, and advising countries to increase sequencing of confirmed cases. Experts emphasize that recombination may occur when multiple strains circulate simultaneously, especially in interconnected sexual networks and international travel corridors.
Global Implications and Critical Next Steps
Health authorities emphasize that although current cases have not demonstrated increased severity or transmissibility, the discovery of recombinant mpox strains signals ongoing viral adaptation and international spread. The high genetic similarity between cases across continents suggests undetected transmission chains may already exist. Maintaining robust genomic surveillance, strengthening diagnostic accuracy, expanding vaccination for high-risk populations, and improving global cooperation are essential to detect new variants early. Continued vigilance will help ensure rapid response, limit spread, and prevent recombinant strains from evolving into more transmissible or dangerous forms. Monitoring viral recombination is now a critical component of long-term mpox containment strategies and global outbreak preparedness.
Reference:
https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON595
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