The U.S. Centers for Disease Control and Prevention (CDC) has issued a health alert in response to a growing mpox outbreak in Central and East Africa, particularly the Democratic Republic of the Congo (DRC). The alert follows the emergence of travel-associated cases in the United States, signaling the need for increased vigilance among healthcare providers and the general public.
The current outbreak is caused by Clade I of the mpox virus, also known as the Congo Basin clade. This strain is historically more severe and associated with higher mortality rates compared to Clade II, which was responsible for the global outbreak in 2022–2023. Laboratory testing has confirmed that the virus strains detected in recent U.S. cases are genetically consistent with those currently circulating in Central Africa, and not related to the less virulent Clade II strains previously identified in the country.
Though the number of U.S. cases remains low, all are linked to recent travel to the DRC and surrounding regions. As of late May 2025, there is no evidence of sustained local transmission within the United States. However, health officials are emphasizing the importance of early detection, particularly among individuals with recent travel history to areas experiencing outbreaks.
The outbreak in the DRC is showing signs of sustained human-to-human transmission, raising concerns about a potential shift in the virus’s epidemiological pattern. Unlike previous outbreaks that disproportionately affected men who have sex with men, the current wave includes cases among men, women, and children. This broader demographic spread may signal evolving transmission dynamics and necessitates wider public health outreach.
Vaccination continues to be a cornerstone of mpox prevention. The JYNNEOS vaccine, which provides protection against both Clade I and Clade II mpox strains, remains available. However, uptake has significantly declined since the peak of the 2022–2023 outbreak. The CDC is urging public health departments to identify individuals at elevated risk—particularly travelers to Central Africa and their close contacts—and ensure they have access to vaccination, testing, and treatment.
Healthcare providers are being advised to consider mpox in the differential diagnosis of patients presenting with compatible symptoms, especially if they have a relevant travel history. Symptoms may include fever, rash, swollen lymph nodes, and muscle aches. Clinicians are also encouraged to promptly report suspected cases to local or state public health authorities and to collect appropriate specimens for laboratory confirmation.
While no travel restrictions have been implemented at this time, travelers to the DRC and nearby countries are advised to take precautions. These include avoiding contact with visibly ill individuals, refraining from handling wild animals, and steering clear of materials potentially contaminated with bodily fluids. Such preventive measures can help reduce the risk of infection and prevent the virus from spreading further.
The CDC continues to monitor the outbreak closely and is committed to issuing updated guidance as more information becomes available. Public health officials are stressing the need for awareness, rapid response, and vaccination to contain the spread of the more virulent Clade I mpox and protect vulnerable populations.
With the potential for further imported cases and the risks associated with a more lethal strain, proactive measures are critical. Continued collaboration between public health authorities, clinicians, and communities will be essential in managing this evolving public health threat.
