The first U.S. case of a more severe strain of MPOX without any recent travel history was discovered in California.
Health officials said this week that the case was confirmed in a Long Beach resident. The patient required hospitalization and is currently isolating and recovering at home.
No other identifying details about the patient were provided, including name, age or gender.
While this is the seventh confirmed case of the more severe virus in the United States this year, it is the first without a known travel history, according to local officials.
Officials said the risk to the public is low and the health department is conducting an investigation, including efforts to determine the patient's potential source of exposure.
Color transmission electron micrograph of MPOX virus particles (blue) found inside infected cells (green) grown in the laboratory.
NIH-NIAID/Image Point FR/BSIP/Universal Images Group (via Getty Images)
“We are taking this issue very seriously and ensuring our community and health care partners remain vigilant so we can prevent additional cases,” Long Beach Mayor Rex Richardson said in a release. “This underscores the importance of continued surveillance, early response and vaccination.”
There are two types of viruses that cause mpox: clade I and clade II, clade roughly meaning they descend from a common ancestral organism. Type I clade has historically been associated with severe illness and death and is endemic in parts of central and west Africa, according to the U.S. Centers for Disease Control and Prevention (CDC).
Clade II caused 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 in the United States
Less severe strains of the virus in the United States continue to circulate at low levels and remain relatively stable.
Parts of Africa have been dealing with continued human-to-human transmission of more severe strains of MPOX. The Centers for Disease Control and Prevention said all six previously confirmed cases of the more severe strain in the United States had recently traveled to areas in Central and East Africa linked to the outbreak.
In November 2024, California reported its first domestic case, a mildly ill traveler from Africa with a more severe strain of the virus.
People with MPOX (formerly known as monkeypox) often develop a rash, which may appear on the hands, feet, chest, face, mouth, or near the genitals, the CDC says.
Most people with MPOX usually recover within two to four weeks without requiring special treatment.
Currently, the JYNNEOS vaccine is a two-dose vaccine approved by the U.S. Food and Drug Administration to prevent smallpox and MPOX and is the only vaccine used in the United States
JYNNEOS vaccine is recommended for use in adults who are at high risk for MPOX, including gay, bisexual, or other men who have sex with men, and who have recent or emerging risk factors such as multiple sex partners, close contact with someone who may have MPOX, or having sex in a commercial setting.
ABC News' Mary Kekatos contributed to this report.