Health Officials Alerted by Severe Mpox Strain Cases in California

Three residents in California have been diagnosed with a strain of mpox known as Clade 1, which is associated with severe illness. This marks the first instance of this virulent strain spreading within the United States, according to health officials. The patients, who had not traveled internationally, are currently recovering at home after being hospitalized.

Clade 1 has been prevalent in central and eastern Africa, where it has led to tens of thousands of infections and hundreds of fatalities. In contrast, Clade 2, which caused a significant outbreak in the U.S. in 2022, resulted in approximately 30,000 infections but typically results in less severe illness. Although Clade 2 continues to circulate at low levels, recent reports indicate a rise in cases across several cities since the summer, with Los Angeles recording 118 cases of mpox this year, a significant increase from none reported in 2024.

The three cases involve one patient in Long Beach and two in Los Angeles. Health officials have not identified a connection among these individuals, raising concerns about potential community spread. The first case was publicly announced by Long Beach officials on Tuesday.

Dr. Kelly Johnson, an infectious disease specialist at the University of California, San Francisco, emphasized the importance of vigilance. While the general public faces a low risk of infection, those with weakened immune systems and men who have sex with men should take extra precautions. “My concern is that person-to-person, community spread could be ongoing,” she stated.

Both Clade 1 and Clade 2 of mpox can be transmitted through intimate contact, household interactions, or by sharing personal items. Symptoms often begin with flu-like signs, followed by a painful rash and lesions.

As health officials continue to monitor the situation, they stress the need for public awareness and prompt reporting of symptoms. The emergence of Clade 1 in California underscores the importance of public health measures to prevent further spread of the virus.