Health officials in Los Angeles County are investigating three cases of a more severe strain of mpox (formerly known as monkeypox), which have emerged without any travel history to affected regions. This marks a significant development, as prior cases in the U.S. linked to the severe strain were traced back to travel in Africa.
Two cases were recently identified among residents of Los Angeles, following the detection of the first domestic case without travel origins in Long Beach. Dr. Muntu Davis, the Los Angeles County health officer, expressed concern about potential local transmission of this more serious type of mpox. "We’re working closely with our partners to identify potential sources and understand how this potentially more serious type of the mpox virus may be spreading," he stated.
Mpox is caused by two types of the virus known as clade I and clade II. Clade I is historically associated with more severe illness and is endemic to parts of central and western Africa. Clade II was responsible for a major outbreak in 2022 that resulted in over 100,000 cases globally, including more than 30,000 in the U.S.
The Centers for Disease Control and Prevention (CDC) indicated that the less severe strain has continued circulating at low levels in the U.S. Parts of Africa are currently experiencing ongoing person-to-person transmission of the more severe strain. Previously, all confirmed cases in the U.S. traced back to travelers who visited areas linked to outbreaks in central and eastern Africa.
Individuals with mpox typically experience a rash that can appear on various parts of the body, including hands, feet, chest, face, mouth, or near the genitals. Although the illness can be concerning, most people recover within two to four weeks without specific treatments.
Currently, the JYNNEOS vaccine, which is a two-dose vaccine approved to prevent both smallpox and mpox, is utilized in the U.S. It is particularly recommended for adults at high risk of mpox, specifically targeting groups such as gay and bisexual men or other men who have sex with men with multiple recent sexual partners or intimate contact with someone suspected of having mpox.