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Atlanta, Georgia – December 27, 2024 – A new recombinant strain of mpox, combining elements of two existing types of the virus, has been detected in England in a traveler recently returned from Asia, raising concerns among scientists about the virus’s continued evolution and potential too evade immunity.
The mpox virus is evolving, and recent research suggests it might potentially be impacting male fertility and becoming more efficient at spreading between people.
- Researchers found the mpox virus persisted in the testes of mice for weeks, potentially impacting male fertility.
- A new strain combining genetic elements of two existing types has been identified in a traveler returning from Asia.
- Newer strains of mpox appear to be less lethal but more easily spread,possibly due to delayed symptom onset.
- The virus continues to evolve, highlighting the need for ongoing surveillance and research.
What is mpox and why is its evolution concerning? Mpox, a virus belonging to the poxvirus family-which also includes smallpox-can cause painful, fluid-filled lesions, fever, and, in severe cases, death. Its ability to adapt and spread, as demonstrated by the 2022 global outbreak and the emergence of new strains, underscores the importance of continued vigilance.
Mpox is Evolving, and Scientists Are Racing to Understand Why
Mpox has been infecting humans since the 1970s, but historically, it rarely spread widely. That changed in the late 2010s with a large outbreak in Nigeria caused by a clade II strain. A similar clade IIb strain then sparked the 2022 global outbreak, infecting more than 100,000 people and continuing to simmer today.
Mpox virus particles (purple) seem to be spreading more easily between people.Credit: NIAID/SPL
More recently,in 2025,infections with clade I mpox-historically causing sporadic,deadly outbreaks in rural Central Africa-increased substantially. A new subtype, clade Ib, began spreading between people in dense urban areas in late 2023, potentially through sexual contact. This mirrors the trajectory of clade II before it went global, according to Boghuma Titanji, an infectious-disease physician at Emory University in Atlanta, Georgia.
