First known U.S. case of new type of mpox found in San Mateo County
San Mateo County health officials have announced the nation’s first known case of a severe form of mpox that has fueled an outbreak of the disease across Eastern and Central Africa.
The county’s health department said Saturday they are working with state and local health officials in responding to the case of clade I mpox, which a person in the county contracted while traveling to Africa. The person appeared to have “mild” symptoms, and is isolating and recovering at home, the health agency said.
The case marked the first known instance of that particular mpox version appearing in the United States, adding to a relatively small but growing number of countries across the world that have discovered cases of it. A different version of the virus, called clade II, has been circulating in the U.S. since 2022 and has sickened at least 108 people in the county and more than 100,000 people worldwide over the last couple years.
The recently detected version is known to cause more severe illness, as well as a higher rate of death, than the version that had previously been found in the United States. Even so, local health officials said there was “very low risk to the public” from the virus, which can cause a painful rash, as well as a fever, chills and muscle aches.
Local health officials are working to reach everyone who may have had contact with the infected individual, and they are expected to do so in this case, said Preston Merchant, a spokesman for the San Mateo County health department.
“There is no concern or evidence that mpox clade I is currently spreading among individuals in San Mateo County or elsewhere in the United States,” the health agency said in a news release Saturday.
The version of the virus detected in San Mateo County lies at the center of an outbreak that has killed more than 1,000 people this year in Central and Eastern Africa, with most of those cases being in the Democratic Republic of Congo. The virus’ spread prompted the World Health Organization in August to declare a public health emergency of international concern, particularly as the virus spread to several other neighboring countries in Africa.
Travelers sicked by the virus in Africa have tested positive for the version in Germany, India, Kenya, Sweden, Thailand, the United Kingdom, Zambia, and Zimbabwe, according to the Centers for Disease Control and Prevention.
The virus usually spreads through skin to skin, intimate and sexual contact, and people can also contract it by directly touching contaminated items and surfaces used by people suffering from mpox, state and federal officials say.
Check back for updates to this developing story.