Assessment of Risk to the U.S. Population from the Ebola Disease Outbreak Caused by Bundibugyo Virus, 2026

Results

The likelihood of Bundibugyo virus infection for the U.S. population was assessed as extremely low. The initial reported case numbers in this outbreak are larger than initial case reports from many recent Ebola disease outbreaks, suggesting that transmission might have been ongoing for an extended period before the outbreak was recognized (3). Despite the large number of cases identified at the time the outbreak was reported, the current likelihood for potential spread of BVD from DRC to the United States, via travelers from DRC who might be infected, is considered very low based on modeling results that consider population movement. These modeling results suggested that the relative risk of importation to the United States compared with other locations was 1.3% (4). In addition, on May 18, enhanced traveler screening and entry restrictions were established to further reduce the potential for importation of BVD into the United States.

If BVD were to be introduced into the United States, based on historical observation and the known epidemiology of BVD, secondary transmission would likely be minimal. The United States has the public health capacity to rapidly implement case identification, laboratory confirmation, isolation of patients, contact tracing, and infection prevention and control measures that can contain and control an outbreak. Although BVD symptoms can appear suddenly and might be nonspecific, these public health measures are highly effective against Ebola disease, in part because the average interval between cases is long (10–16 days), and because persons are not known to be infectious before the onset of symptoms (5). Only 11 persons infected with Ebola disease have ever been treated in the United States; all were associated with the 2014–2016 Ebola virus disease outbreak in West Africa (6). Despite two instances of secondary transmission to U.S. health care workers during that outbreak, no community spread occurred in the United States. Although the likelihood of infection for the general U.S. population is low, the likelihood of infection might be higher among U.S. health care workers practicing in or who have recently returned from affected regions in DRC and Uganda based on possible exposure risks.

Impact of Infection

The impact of infection, based on the standardized framework, was assessed as high, primarily based on the severity of the illness, lack of available medications and vaccines, and resources required to respond to the current outbreak. In the two previously identified outbreaks of BVD in Uganda in 2007 and DRC in 2012, case-fatality rates ranged from 25% to 50%. However, many of the deaths in these outbreaks occurred in locations where health resources are limited; clinical outcomes might improve with the specialized care available in the United States.

No approved vaccines or medications are currently available for BVD. A licensed vaccine and two licensed monoclonal antibody products have been used in previous outbreaks of Ebola disease caused by a different virus (species Orthoebolavirus zairense); whether these products are effective against BVD is unknown. While investigational medications are being evaluated, treatment for BVD is currently limited to supportive care.

Preventing spread of Bundibugyo virus requires considerable public health resources and risk communication. Public health interventions could include extensive contact tracing activities, quarantine of 21 days for persons with high-risk exposures, and stringent infection prevention and control measures for health care workers and laboratory personnel. Even very limited numbers of BVD cases in the United States might cause substantial concern among the public, possibly with some disruption of normal societal activities and to health care facilities.

Confidence Level

Confidence in this assessment of BVD risk to the U.S. population during the next 3 months was assessed as moderate, based on availability of credible information from reliable sources, requiring minimal assumptions to be made for the analysis. The United States is prepared to respond to imported cases, and the largest previous outbreaks of Ebola disease in other countries led to very few cases within the United States. However, this assessment also recognizes uncertainties about the epidemiology of BVD, the scope and geographic spread of the outbreak, and the potential timelines for implementation of interventions.