Clade 2 is found in West Africa and in 2022 sparked a global epidemic and its own PHEIC, when it spread to more than 100 countries, predominantly affecting gay and bisexual men.

But the new outbreak is driven by clade I, which causes more severe disease.The subtype that’s responsible for most of the ongoing spread, clade Ib, is relatively new.

By comparison, clade II outbreaks in Africa have generally had a mortality rate of around 1%, and just 0.2% of cases linked to the 2022 global outbreak were fatal.

While an outbreak of clade II mpox has been seen in the U.S. and elsewhere since 2022, the first U.S. clade I case was confirmed this weekend by the California Department of Public Health (CDPH).

The United States’ first known case of a more severe strain of mpox was confirmed in California, the US Centers for Disease Control and Prevention said Saturday. The risk of clade I mpox to the ...

Clade II — Clade II is less severe. It fueled the 2022 global outbreak, according to the Miami Herald, which led to more than 32,000 infections in the U.S. What do we know about mpox clade 1b?

The risk of clade I mpox to the public remains low, and there continue to be sporadic clade II mpox cases in the United States," the CDC said. Clade II mpox has been in the U.S. since a larger ...

While this the first case of clade I to be announced in the U.S., 3,004 cases of mpox clade II have been recorded since Jan. 1, 2024, according to CDC data.

Clade I is generally considered more transmissible and more severe than clade II, which drove the global mpox outbreak that peaked in August 2022 and had a death rate of 0.2%.

Clade I has historically caused more severe illness compared to clade II, the strain associated with other U.S. cases of mpox. California public health officials said recent infections indicate ...