The CDC issued a health alert Dec. 7 advising clinicians and public health officials in the U.S. to watch for cases of mpox and enhance surveillance as a more transmissible and severe subtype of the disease, clade I, spreads in the Democratic Republic of Congo.
No clade I cases have been reported in the U.S. at this time, the CDC said.
"However, clinicians should be aware of the possibility of [clade I mpox] in travelers who have been in DRC," the alert said. "Clinicians should notify their state health department if they have a patient with mpox-like symptoms, which may include a diffuse rash and lymphadenopathy, and recent travel to DRC. Clinicians should also submit lesion specimens for clade-specific testing of these patients."
The 2022-23 global outbreak was associated with the clade II monkeypox virus, which has predominantly affected gay and bisexual men, as well as other men who have sex with men. The Jynneos mpox vaccine should be effective against both clades, but the CDC noted coverage in the U.S. remains low, with only 1 in 4 people who are eligible to receive it having gotten both doses necessary for greater protection.
The health alert also advised public health departments to enhance surveillance efforts in case the clade I strain is detected in the U.S. Alongside the alert, the agency issued a travel health notice recommending people traveling to the DRC avoid close contact with anyone who is ill and dead or wild animals.
In the DRC, infections from the clade I subtype are spreading through sexually associated human-to-human contact, according to the alert. Since the start of the year, 12,569 suspected cases have been reported in the DRC, including 581 deaths — a "substantial increase from the median 3,767 suspected mpox cases" reported annually in the region from 2016 to 2021.