The Centers for Disease Control and Prevention (CDC) is issuing this Health Alert Network (HAN) Health Update to provide additional information about the ongoing outbreak of clade I monkeypox virus (MPXV), the virus that causes mpox, in Central and Eastern Africa.

This report is an update to HAN Health Advisory 501 issued in December 2023 and HAN Heath Update 513 in August 2024. MPXV transmission in countries where the virus is endemic is typically via exposure to infected wildlife with subsequent person-to-person spread via close contact (including intimate or sexual contact) with a person with mpox, or direct contact with their respiratory secretions (e.g., snot, mucus) or contaminated objects (e.g., bedding). During the global clade II outbreak, human-to-human transmission of mpox has been predominantly spreading through sexual contact.

During 2024, the Democratic Republic of the Congo (DRC) has reported >21,000 suspected clade I mpox cases, its largest annual number on record. Although the proportion of people impacted in DRC (population >99 million) is relatively low, cases are more widespread than in any previously reported DRC outbreak. Clade Ia mpox cases are impacting the western part of DRC (particularly the rural Équateur Province). No cases of clade Ia mpox have been reported outside Central African countries where clade Ia MPXV is endemic. Clade Ib mpox cases are impacting the eastern part of DRC and have been spread through regional travel. Early data indicate that a large proportion of clade Ib mpox cases among adults has been associated with sexual contact, including via ongoing transmission believed to be occurring in some countries where the virus is not normally found.

Travelers to DRC or other countries with sustained spread of clade I mpox, regardless of sexual orientation or gender identity, should be made aware of activities associated with cases and should be vaccinated with two doses of JYNNEOS if they anticipate certain sexual exposures while traveling. Active monitoring for mpox continues to occur in the United States. Although the United States continues to be affected by an ongoing global outbreak of clade II mpox that began in 2022, no domestic cases of clade I mpox have been identified in the United States at this time. Continue to follow CDC’s current vaccine guidance to prevent clade II MPXV infection, which continues to circulate in the United States, and will also help protect against clade I MPXV.

Please see the full CDC Health Update here:

https://emergency.cdc.gov/han/2024/han00516.asp