
An ongoing outbreak of the clade 1 mpox virus in the Democratic Republic of the Congo (DRC) poses a threat to the United States, authors write in Morbidity and Mortality Weekly Report. Clade 1 is more deadly and severe than the clade 2 virus that caused a global outbreak among men who have sex with men (MSM) in 2022.
Both clades of the virus are endemic in the DRC, but the country noted an uptick in clade 1 cases in 2023 and 2024, with 19,919 suspected cases reported and 975 (4.9%) deaths. Cases are spreading both among traditional household transmission routes, and among sexual networks, including MSM and sex workers.
Two thirds of cases in kids under 15
Of note, a large proportion of the current outbreak is among children ages 15 and under, representing 67% of suspected cases and 78% of suspected deaths. Children aged 12 to 59 months accounted for 28% of all suspected cases.
Beginning December 7, 2023, the US Centers for Disease Control and Prevention urged clinicians to consider clade 1 infections in persons with mpox signs and symptoms who had recently been in DRC, and conduct clade-specific testing for those patients.
To date, no cases of clade I mpox have been reported in the United States or in any countries where the virus is not endemic.
"To date, no cases of clade I mpox have been reported in the United States or in any countries where the virus is not endemic. However, given the documented sexual transmission of clade I MPXV in DRC, persons engaging in certain sexual behaviors (e.g., MSM with multiple sexual partners and sex workers) might be at increased risk if clade I mpox is introduced into the United States," said authors.
The authors warned that 19 recent cases of clade 1 detected in DRC's neighboring Republic of the Congo suggests the cases in the DRC, "pose a new risk for global spread if the virus is not urgently contained.
"In addition to preparing for the possibility of spread beyond DRC, support to DRC from global partners is needed as the country works to increase testing and surveillance for clade I MPXV."