The U.S. Center for Disease Control and Prevention (CDC) has issued an official Health Alert Network (HAN) advisory in response to a growing mpox outbreak in Central Africa, particularly the Democratic Republic of the Congo (DRC).
The outbreak has led to a small number of travel-associated mpox cases diagnosed in the United States since 2024.
This outbreak involves Clade I of the mpox virus, a variant historically associated with more severe illness and a higher case fatality rate than Clade II, which was responsible for the 2022–2023 global outbreak.
The Clade I of the mpox virus is also known as the Congo Basin clade and is one of two types of mpox (formerly known as monkeypox) viruses.
Laboratory testing has confirmed that the virus detected in the current U.S. cases is genetically consistent with strains circulating in Central Africa and distinct from the Clade II strain previously seen in the United States.
Disease contained in the U.S.
As of May 2025, there is no evidence of sustained local transmission in the U.S., but the CDC is urging healthcare providers to remain alert, especially when evaluating patients with recent travel to the DRC or neighboring countries.
According to the CDC, the outbreak in the DRC shows signs of sustained human-to-human transmission.
Mpox cases have been reported among men, women, and children, suggesting a possible shift in transmission dynamics compared to previous outbreaks that largely affected men who have sex with men.
Vaccination remains a key preventive measure. The CDC supports the continued use of the JYNNEOS vaccine, which is effective against both Clade I and Clade II strains.
However, the agency notes that uptake of the vaccine has declined since the height of the previous outbreak. The HAN advisory encourages health departments to identify individuals at risk and ensure they have access to testing, treatment, and vaccination.
To support early detection and reduce the risk of further spread, the CDC recommends that clinicians:
- Consider mpox in the differential diagnosis of patients with compatible symptoms and relevant travel history.
- Promptly report suspected cases to local or state public health authorities.
- Collect specimens for confirmatory testing through the CDC or designated public health laboratories.
US CDC issues warning
No travel restrictions have been issued at this time, but travelers to the DRC are advised to avoid close contact with sick individuals, wild animals, and materials contaminated with bodily fluids.
The CDC continues to monitor the situation and will provide updated guidance as more information becomes available.
For now, health officials are emphasizing early recognition and public health response, given that Clade I mpox presents more serious health risks and has resulted in fatalities in affected countries abroad.
