California authorities confirm first US case of serious mpox strain without travel history

The first US case of a more serious strain of mpox with no recent travel history has been identified in California.

Health officials said this week that the case was confirmed in a Long Beach resident. The patient required hospitalization and is currently in isolation and recovering at home.

No other identifying details were provided about the patient, including name, age or gender.

Although this is the seventh case of the most serious strain confirmed in the United States this year, it is the first with no known travel, according to local authorities.

Officials say the risk to the general public is low and the Department of Health is investigating, including identifying potential sources of patient exposure.

“We are taking this very seriously and are ensuring our community and health care partners remain vigilant so we can prevent additional cases,” Long Beach Mayor Rex Richardson said in a news release. “This highlights the importance of continued surveillance, rapid response and vaccination.”

There are two types of viruses that cause mpox: clade I and clade II, with clade roughly meaning that they are descended from a common ancestor organism. Clade I has historically been associated with severe disease and death, and is endemic in parts of central and west Africa, according to the Centers for Disease Control and Prevention (CDC).

Clade II was responsible for a large outbreak that peaked in the summer of 2022, resulting in more than 100,000 cases in 122 countries, including more than 30,000 cases in the United States.

In the United States, the less serious strain continued to circulate at low levels and remained relatively stable.

Parts of Africa are experiencing sustained human-to-human spread of the most serious strain of mpox. The six previously confirmed cases of the most serious strain in the United States involved people who had recently traveled to areas associated with the outbreak in central and eastern Africa, according to the CDC.

In November 2024, California reported the nation’s first case of the more serious strain in a traveler from Africa who suffered mild illness.

People with mpox, formerly known as monkeypox, often have a rash that may be located on the hands, feet, chest, face, mouth or near the genitals, the CDC said.

Most people with mpox usually recover within two to four weeks without specific treatment.

Currently, the JYNNEOS vaccine, a two-dose vaccine approved by the Food and Drug Administration to prevent smallpox and pox, is the only vaccine used in the United States.

The JYNNEOS vaccine is recommended for adults at high risk for mpox, which includes gay, bisexual, or other men who have sex with men and who have recent or future risk factors such as multiple sexual partners, intimate contact with someone who may have mpox, or sex in commercial settings.

ABC News’ Mary Kekatos contributed to this report.