Notes from the Field: Characteristics and Monitoring of the 2026 Outbreak of Ebola Disease Caused by Bundibugyo Virus — Democratic Republic of the Congo, August 2026

Investigation and Outcomes

Background

The 2026 Ebola DRC outbreak caused by Bundibugyo virus is now the second largest Ebola outbreak ever recorded. As of August 21, 2026, DRC reported 5,458 confirmed cases and 2,606 (48%) confirmed deaths. Compared with previous Ebola outbreaks, the increase in cases in DRC is unprecedented, with approximately 5,000 cases in 100 days (Ebola Outbreak: Current Situation | CDC). Cases have been reported from six of the 26 DRC provinces (Bas-Uélé, Haut-Uélé, Ituri, North Kivu, South Kivu, and Tshop), affecting 57 of 151 health zones in the affected provinces. Ituri province remains the outbreak epicenter, accounting for 84% of reported cases. Strategies known to control Ebola outbreaks include community-based surveillance, case detection alert notifications,* rapid and in-depth case investigations, identification and monitoring of contacts, infection control measures (e.g., prompt isolation of persons with suspected or confirmed Bundibugyo virus disease [BVD]), rapid diagnostic testing, mortality surveillance, and safe and dignified burials (SDBs).^†

Data Source

Operational indicators for five domains have been generated based on experience with previous Ebola outbreaks, including DRC’s 2018 outbreak (3) (Table). Targets reflect the levels necessary to end the outbreak. The DRC Ministry of Public Health prepares publicly available daily situation reports, and CDC abstracts data from these reports to evaluate the established indicators each day. Indicator data are monitored over time to assess the outbreak trajectory. This activity was reviewed by CDC, deemed not research, and conducted consistent with applicable federal law and CDC policy.^§

Operational Indicator Analysis

Nearly all operational indicators remain below identified targets (Table). Operational indicator values were calculated for the 21-day period of July 31–August 21. The average percentage of alerts investigated within 24 hours (last reported August 5, 2026) was 83% (target = >90%). An average of 10.6 contacts were identified per confirmed case (target = ≥20), suggesting underreporting and underascertainment of case contacts. The percentage of confirmed new cases previously identified as known contacts (last reported July 12, 2026) was 15%–20% (target = >90%); this suggests that most cases are occurring outside known transmission chains. In addition, more than one half (59%) of confirmed Ebola deaths are occurring outside an Ebola treatment unit (ETU) (target = 0%), suggesting insufficient ETU capacity, fear of ETUs, and ongoing spread through unidentified transmission chains. Laboratory testing was performed for 72% of validated alerts (target = >90%), indicating that a substantial number of suspected cases remain untested. Test positivity was 24%, with a target of 0%. Although the national ETU bed occupancy was 64%, meeting the target of <80%, occupancy varied substantially by health zone, with some facilities unable to isolate all infected persons and reporting occupancies as high as 140%. Fewer than one half (49%) of affected health zones had at least one SDB team (target = 100%). Current data were not available for several response indicators, such as percentage of persons with confirmed BVD receiving prompt isolation (target = >90%) and percentage of deaths with SDBs (target = 100%), underscoring ongoing data gaps in this complex public health response.

Preliminary Conclusions and Actions

As of August 21, 2026, most operational indicator measures remained below established response targets, and data for others were unavailable, indicating gaps in surveillance, contact tracing, laboratory testing, health care–seeking, isolation, and SDB capacity that limit control of the ongoing outbreak. These missing data and operational gaps, together with continued geographic expansion of the outbreak, a high percentage of deaths occurring outside ETUs, and a low percentage of cases among persons previously identified as contacts, indicate uncontrolled expansion of the outbreak. Public health response activities are complicated by a protracted complex humanitarian emergency in the eastern part of DRC, including armed conflict, limited health infrastructure, population displacement and mobility, and constraints on access to affected communities.

Containment and control of the 2026 Ebola disease outbreak requires integration and coordination of at least five response areas: 1) expansion of community-based surveillance systems ensuring rapid investigation of alerts; 2) improvements in contact tracing completeness and timeliness; 3) expansion of treatment and isolation capacity in affected health zones; 4) increased laboratory testing capacity, enabling prompt case identification; and 5) ensuring SDBs in affected health zones.

In addition, collecting robust, high-quality data regarding these operational actions is essential at the health zone level; CDC’s continued support to the DRC Ministry of Public Health and partners with improving data collection is critical. Collecting data at the level of the health zone facilitates timely local outbreak response decisions. Rapidly enhancing international humanitarian coordination and mobilizing global technical, operational, and other needed support are critical for accelerating the response and controlling the outbreak.