California officials confirm 1st US case of severe mpox strain with no travel history
October 16, 2025
The first U.S. case of the more severe Clade I mpox strain without recent travel history marks a concerning shift in the virus’s domestic transmission. Detected in Long Beach, California, the case underscores the need for heightened vigilance, rapid contact tracing, and continued vaccination among at-risk groups. Although officials say the public risk remains low, the case signals that containment strategies must adapt as the virus evolves beyond imported infections. Sustained public health surveillance, early testing, and equitable access to the JYNNEOS vaccine are vital to preventing wider spread and ensuring the U.S. remains prepared for future orthopoxvirus threats.
The confirmation of the first U.S. case of Clade I mpox without recent travel history marks a potential turning point in domestic surveillance and outbreak preparedness. Identified in Long Beach, California, the case involves a hospitalized patient now recovering at home. While health officials maintain that the overall risk to the public is low, the detection of a locally acquired Clade I infection raises concern about undetected community transmission.
Clade I mpox, which has historically caused higher rates of severe illness and death in parts of Central and West Africa, differs from the milder Clade II strain responsible for the 2022 global outbreak. That event led to more than 100,000 cases worldwide and over 30,000 in the United States, primarily among gay, bisexual, and other men who have sex with men. The resurgence of a more virulent clade reinforces the need for ongoing vigilance even as U.S. case numbers remain low.
Health officials in Long Beach are working to trace potential exposures, monitor contacts, and strengthen awareness among healthcare providers. Mayor Rex Richardson emphasized the importance of continued surveillance, early response, and vaccination efforts to prevent additional cases. The Centers for Disease Control and Prevention continues to recommend the two-dose JYNNEOS vaccine for individuals at elevated risk, including those with multiple sexual partners or recent potential exposures.
The appearance of this case without travel history highlights the interconnectedness of global and local health. Pathogens that once seemed geographically confined can quickly adapt and spread across borders. Preventing future outbreaks will depend on sustained investment in laboratory capacity, transparent communication, and public trust in vaccination. As the mpox landscape evolves, preparedness must evolve with it to protect both vulnerable populations and the wider community.