Two people in California have been diagnosed with mpox, and health officials say these may be the first U.S. cases linked to local transmission of a different version of the virus. The Long Beach Department of Health and Human Services confirmed the first case after state lab testing, and Los Angeles County health officials reported a second similar case.
Authorities say the overall risk to the public remains low. These are not the first U.S. cases of clade I mpox, but the previous six cases involved international travelers believed to have been infected abroad.
Both patients were hospitalized and are now recovering at home. Officials have not released further details about the individuals.
Long Beach, which operates its own city health department, is located in Los Angeles County. Investigators there have not found any close contacts who traveled abroad or confirmed additional cases. Some close contacts of the infected person have received a vaccine, according to Nora Balanji, communicable disease coordinator for the Long Beach department.
“We don’t have any proof that there has been ongoing community transmission,” Balanji said. “It’s something we’re looking into. That’s something we’re concerned about.”
Mpox, also known as monkeypox, is a rare disease caused by a virus related to smallpox. It is typically found in parts of Africa. Symptoms can range from fever, chills, and body aches to more severe cases with lesions on the face, hands, chest, and genitals.
Clade II of the virus caused an international health crisis in 2022, mainly affecting men who have sex with men and leading to about 500 U.S. cases per day at its peak. Most infections were not fatal, but many patients experienced painful skin lesions for weeks. The outbreak subsided later that year, partly due to the Jynneos vaccine.
Clade I, the other version of the virus, can also spread through sexual contact and other forms of close contact. In Africa, it has infected a wider range of people, including children. A newer form of clade I has spread widely in eastern and central Africa, prompting the World Health Organization to declare a public health emergency, though the situation has since improved.
Dr. William Schaffner, an infectious diseases expert at Vanderbilt University, said, “it’s concerning if this virus has come here and now is starting to be transmitted from person to person.”
The new cases come during a federal government shutdown, which has led to layoffs at the Centers for Disease Control and Prevention (CDC). Balanji noted that some CDC experts are still available for consultation, but Schaffner warned that “the longer the shutdown, the more impaired public health responses are to any outbreaks.”
A spokesperson for the U.S. Department of Health and Human Services directed questions to local health officials.
