Locally Acquired Mpox Strain in U.S. Exhibits Greater Severity

Authorities in California have reported two cases of a more serious form of mpox that seem to have been acquired locally, lacking any travel history to regions where the virus is usually endemic.

Local Cases of Severe Mpox in Los Angeles

The Los Angeles County Department of Public Health announced that an adult patient, who had been hospitalized due to mpox, is currently recuperating at home. This individual has no recent travel history to areas predominantly affected by the virus, which are mainly found in Africa. This marks the second instance of a locally contracted clade I infection in Los Angeles County, occurring shortly after a previously reported case.

Clade I Mpox: A Comparison

Clade I mpox is noted by health professionals to potentially cause more serious health issues compared to clade II mpox, which has been responsible for several outbreaks in the United States. The fatality rate for clade II is estimated to be between less than 1% and 4%, whereas for clade I, it ranges from 1% to 10%. Of note, clade I has been increasingly reported in children in the Democratic Republic of the Congo, unlike clade II.

National and International Context

Other instances of clade I mpox across the United States have been linked to individuals who recently visited affected areas abroad, as per the Centers for Disease Control and Prevention (CDC). Besides these human cases, the strain has also been identified through wastewater testing.

Health Concerns and Transmission

Dr. Muntu Davis, Los Angeles County Health Officer, expressed concerns about the detection of clade I mpox cases, which are potentially more severe than the clade II variant. He emphasized that mpox generally spreads through close and intimate interactions with symptomatic individuals, often occurring during sexual activities.

The virus is transmitted through direct human contact, such as sexual relations, massages, or cuddling, and can also spread within households or via shared personal belongings.

Risk and Recommendations

The risk to the wider public is still considered low, but precautions are advised for certain groups. This includes gay, bisexual, or other men who engage in sexual activities with men.

Dr. Davis stressed the importance of early detection, testing, and vaccination efforts to manage the virus's spread, recommending full vaccination for optimal protection against mpox.

Symptoms and Progression

Both clade I and II mpox may start with symptoms resembling the flu, later developing into a rash. The CDC notes that signs typically manifest within three weeks post-exposure.

According to Johns Hopkins, rashes associated with clade I often spread extensively over the body, including the face and torso, while clade II rashes may not be as widespread.