Severe Mpox Strain Detected in California Without Travel History

On October 17, 2025, health officials in California confirmed the first U.S. case of a more severe strain of mpox in a Long Beach resident with no recent travel history. The patient required hospitalization but is now isolating and recovering at home.

This case marks the seventh confirmed instance of the more severe clade I strain of the mpox virus in the United States this year. However, it is the first such case without any known travel to areas associated with the outbreak in central and eastern Africa.

While the risk to the general public remains low, local authorities are taking the situation very seriously. The Long Beach Health Department is conducting an investigation to identify the patient's potential sources of exposure and prevent any further spread of the virus.

"This underscores the importance of continued surveillance, early response and vaccination," said Long Beach Mayor Rex Richardson. Health officials are urging the community and healthcare providers to remain vigilant in order to detect and contain any additional cases.

The mpox virus has two main strains, with clade I historically associated with more severe illness and higher mortality rates. The less severe clade II strain has been responsible for the larger outbreak that peaked in the summer of 2022, leading to over 100,000 cases globally and more than 30,000 in the U.S.