Summary
The Centers for Disease Control and Prevention (CDC) is issuing this Health Alert Network (HAN) Health Advisory about a new outbreak of Ebola virus disease (EVD) in the Democratic Republic of the Congo (DRC). EVD is a severe illness and is often fatal.
Currently, no suspected, probable, or confirmed EVD cases related to this outbreak have been reported in the United States or outside of the DRC. The risk of spread to the United States is considered low at this time. As a precaution, this Health Advisory summarizes CDC recommendations for U.S. public health departments, clinical laboratories, and healthcare workers about potential EVD case identification, testing, and biosafety considerations in clinical laboratories.
On September 8, 2025, CDC issued a Travel Health Notice for people traveling to the DRC. CDC recommends that all travelers to the affected health zones in DRC avoid contact with ill people during travel and monitor themselves for symptoms of EVD while in the outbreak area and for 21 days after leaving. Travelers who develop symptoms during this time should self-isolate and contact local health authorities or a clinician. At this time, CDC is not recommending additional assessments or monitoring of travelers arriving from DRC by the jurisdictional health departments unless mentioned in the existing VHF guidance provided below.
Background
On September 4, 2025, the Ministry of Public Health, Hygiene and Prevention in the DRC declared an EVD outbreak caused by re-emergence of Ebola virus (species Orthoebolavirus zairense) in the Kasai Province. As of September 18, 37 confirmed cases and 19 deaths, including 4 health workers, have been reported (case fatality rate [CFR] 51%). This is the 16th Ebola disease outbreak reported in DRC since the virus was discovered there in 1976. The Kasai Province has experienced two previous EVD outbreaks: one in 2007 with 264 cases and 187 deaths (CFR 71%), and another in 2008 with 32 cases and 15 deaths (CFR 47%). No suspected, probable, or confirmed EVD cases related to the current outbreak have been reported outside of the DRC or in the United States.
The current outbreak is centered in the Bulape and Mweka health zones within the Kasai Province in the DRC. The index case was a 34-year-old pregnant woman (34 weeks gestation) who was admitted to a local hospital on August 20 with symptoms including high fever, bloody diarrhea, hemorrhaging (nasal, oral, anal), vomiting, and severe physical weakness. The patient died on August 25 from multiple organ failure. Two healthcare workers who cared for the patient later developed similar symptoms and died. Blood and buccal swab specimens tested on September 3 at the country’s National Institute of Biomedical Research (INRB) confirmed an outbreak of EVD caused by Ebola virus (species Orthoebolavirus zairense). Genomic sequencing performed by INRB suggests that this is a new introduction of the disease into the human population from an unknown infected animal.
CDC is working with DRC’s Ministry of Public Health, Hygiene and Prevention to support the response to this outbreak. CDC deployed three experts from its Atlanta headquarters and two from the CDC DRC country office to provide technical expertise in surveillance, case investigation, and contact tracing. Resources are being mobilized to strengthen laboratory testing, epidemiology, and infection prevention and control measures. Additional cases may be retrospectively identified as the source of the outbreak remains unknown.
The risk of spread to the United States is considered low at this time. Access to the outbreak region is difficult and there are no direct flights between the DRC and the United States. However, travelers from affected areas in DRC might enter the United States on flights connecting through other countries. Therefore, as a precaution, CDC is working to raise awareness of this outbreak among travelers, public health departments, public health and clinical laboratories, and healthcare workers in the United States. Healthcare providers should be alert and evaluate any patients suspected of having EVD. It is important for clinicians to obtain a detailed travel history from patients with suspected EVD, especially those who have been in affected areas of the DRC recently. Early consideration of EVD in the differential diagnosis is important for providing appropriate and prompt patient care and diagnostics, and to prevent the spread of infection.
Ebola Disease
Ebola disease is caused by a group of viruses known as orthoebolaviruses (formerly ebolavirus). Ebola disease most commonly affects humans and nonhuman primates, such as monkeys, chimpanzees, and gorillas. Four orthoebolaviruses cause illness in people, presenting as clinically similar disease:
- Ebola virus (species Orthoebolavirus zairense) causes Ebola virus disease.
- Sudan virus (species Orthoebolavirus sudanense) causes Sudan virus disease.
- Taï Forest virus (species Orthoebolavirus taiense) causes Taï Forest virus disease.
- Bundibugyo virus (species Orthoebolavirus bundibugyoense) causes Bundibugyo virus disease.
The incubation period for EVD ranges from 2 to 21 days after exposure. A person infected with an orthoebolavirus is not considered contagious until after symptoms appear. Early “dry” symptoms include fever, aches, pains, and fatigue and later “wet” symptoms include diarrhea, vomiting, and unexplained bleeding. Ebola disease is spread through contact (through broken skin or mucous membranes) with the body fluids (e.g., blood, urine, feces, saliva, semen, or other secretions) of a person who is sick with or has died from Ebola disease. Ebola disease is also spread by infected animals, or through contact with objects like needles that are contaminated with the virus. Ebola disease is not spread through airborne transmission.
An Ebola vaccine (ERVEBO®) is approved by the U.S. Food and Drug Administration (FDA) for preventing EVD due to Ebola virus (species Orthoebolavirus zairense). ERVEBO® should only be given to patients who meet specific criteria. Two FDA-approved treatments are currently available to treat Ebola virus infection: Inmazeb™ and Ebanga™.
In the absence of early diagnosis and treatment, EVD has a high rate of fatality. Previous outbreaks of EVD have had case fatality rates as high as 80 to 90%. With intense supportive care and fluid replacement, fatality rates might be lower.
CDC has developed recommendations for U.S.-based organizations (e.g., nongovernmental, faith-based, academic, or aid organizations) with staff working in affected areas: Recommendations for Organizations Sending U.S.-based Personnel to Areas with VHF Outbreaks.
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