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As of February 19, 2025

ob体育 assessed the risk posed by the Sudan virus disease (SVD) outbreak in Uganda, a type of Ebola disease caused by the Sudan virus, to the United States general population over the next three months. The risk to the general U.S. population is low, with moderate confidence.

The purpose of this assessment is to inform U.S. preparedness efforts for the outbreak of SVD in Uganda. The assessment relied on subject matter experts evaluating a range of evidence related to risk, including epidemiologic data from the outbreak in Uganda and historical data on SVD epidemiology and clinical severity. We continue to monitor the situation and will update this risk assessment if new information warrants changes.

Risk assessment for the general population in the United States

Likelihood

The likelihood of Sudan virus infection for the general U.S. population is extremely low. Factors that informed our assessment of likelihood include the following:

• As of February 10, 2025, there have been nine confirmed cases and one death in and around the capital city of Kampala, UgandaA.
  • The initial case was confirmed postmortem on January 30, 2025. The patient, who died at the largest public hospital in Uganda, had visited multiple hospitals and a traditional healer before he died on January 29. The confirmed secondary cases are family members and health care workers who cared for the index patient.
  • Kampala is the largest city in Uganda, with a high population density. However, Uganda has experience controlling SVD outbreaks and has acted rapidly to control the outbreak by activating an emergency operations center, contact tracing, and point of entry and exit screening.
• There are no known cases of SVD in the United States. However, there remains a risk of potential spread from Uganda to the United States via travelers from Uganda who may be infected.
  • Broader spread of Sudan virus in Uganda and neighboring countries would increase the risk of importation to the United States. The daily number of passengers entering the United States whose flights originate in Uganda is low. There are no direct commercial flights from Uganda to the United States.
• If Sudan virus were introduced to the United States through a traveler, we expect there could be limited spread before control measures are implemented, as symptoms can appear suddenly and may be non-specific.
  • The United States has a high capacity for implementing case identification, isolation, contact tracing, and infection prevention and control measures that are likely to stop an outbreak before it grows significantly. These measures are likely to be effective in part because the average interval between subsequent cases is long (10-14 days) and transmission is unlikely to occur before symptoms appear.
  • Only 11 persons infected with Ebola virus have ever been treated in the United States; all cases were associated with the 2014–2016 Ebola outbreak in West Africa. Of these, nine cases were imported, two introduced through travel and seven brought by medical evacuation. Two of the 11 cases occurred in healthcare workers who treated a case. Despite these two instances of secondary transmission, there was no community spread in the United States.
• Infection is more likely in U.S. healthcare workers practicing in or recently returned from Uganda than in the general U.S. population. United States healthcare workers would also have an elevated chance of infection if a patient with unrecognized Sudan virus infection were to seek care in the United States.
  • Healthcare workers have been disproportionately affected in past Ebola disease outbreaks.
  • Sudan virus transmission in this group could result in spread to close contacts if not detected immediately.

Impact

The impact of infection for the general U.S. population is high. Factors that informed the assessment of impact included the following:

• SVD is a serious, deadly disease. This outbreak of SVD is caused by the Sudan virus; in past outbreaks, approximately 50% of people infected with this virus died. However, many patients who died in past outbreaks were in locations without access to the level of care available in U.S. intensive care units.
• People in the United States do not have immunity to Sudan virus, and there are no Food and Drug Administration (FDA)-approved treatments or vaccines currently available. However, experimental in Uganda in response to the current outbreak as part of an ongoing clinical trial. These could likely be utilized in limited scenarios in the United States, should the need arise and if appropriate FDA mechanisms are issued. In addition, there are experimental monoclonal antibodies that appear to be effective and have been used in previous outbreaks. Beyond this, treatment is limited to supportive care.
• Even very limited Sudan virus spread in the United States could cause significant panic and fear among the public, and disruption to normal societal activities. In addition to the lives directly affected, Sudan virus spread would require significant public health resources, risk communication, and community engagement. Containment requires extensive contact tracing activities, long quarantine for persons with high-risk exposures (up to 21 days), and stringent barrier protection measures for healthcare workers and laboratory personnel.

Confidence

We have moderate confidence in this assessment.

We note some uncertainty in the implications for the United States of the SVD outbreak in Uganda, as the conditions of the current outbreak are still emerging.

Factors that could change our assessment

We continue to monitor for additional factors that could change our risk assessment, including:

• Detection of SVD cases in the United States
• The outbreak in Uganda intensifying or spreading to other countries, in the region or globally, raising the likelihood of imported cases in the United States
• Any evidence suggesting increased transmissibility compared to past outbreaks
• Any evidence of changed clinical severity compared to past outbreaks
• Successful clinical trials for vaccines and/or treatments

Background

Risk Assessment Methods

ob体育 subject matter experts specializing in risk assessment methods, infectious disease modeling, global health, and Ebola virus and other viral hemorrhagic fevers collaborated to develop this rapid assessment. Experts initially convened in early February 2025 to discuss the need for an assessment examining the risks to the United States posed by the Sudan virus outbreak in Uganda and key evidence related to this outbreak. To conduct this assessment, experts considered evidence including epidemiologic data from the ongoing Sudan virus outbreak in Uganda, and historical data on Ebola disease outbreaks.

Risk was estimated by combining the likelihood of infection and the impact of the disease. For example, low likelihood of infection, combined with high impact of disease, would result in moderate risk. The likelihood of infection refers to the probability that members of the general U.S. population would acquire Sudan virus over the next three months, which in turn depends on the likelihood of exposure, infectiousness of the virus, and susceptibility of the population. The impact of infection considers several factors affecting the consequences of infection, including the severity of disease, level of population immunity, availability of treatments and vaccines, and necessary public health response resources. A degree of confidence was assigned to each level of the assessment, taking into account evidence quality, extent, and corroboration of information.

For more details on our methods, please see our rapid risk assessment methods webpage.