Dr. Céline Goundermedical correspondent, CBS News · physician, epidemiologist, medical journalist

Modeled Scenario Projections for the Ebola Disease Outbreak Caused by Bundibugyo Virus, 2026 MMWR

PDF · 5 Jun 2026

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This CDC MMWR early‑release report presents a quantitative modeling analysis of the 2026 Bundibugyo virus disease (BVD) outbreak in the Democratic Republic of the Congo and Uganda. Using a branching‑process transmission model calibrated to three plausible cumulative death counts (50, 100, 200 deaths as of 24 May 2026), the authors simulate 500 outbreak realizations for each calibration and project epidemic trajectories over the subsequent 90 days under four isolation‑intervention scenarios (20 %, 50 %, 70 %, 95 % of symptomatic cases detected, isolated, and treated). The model incorporates fixed infection‑to‑symptom, symptom‑to‑death, and symptom‑to‑recovery intervals, draws basic reproductive numbers (R₀) from published Ebola estimates, and assumes a 2‑day delay to isolation after symptom onset. Results show that with low isolation (20 %) the probability of ≥20 000 cases within three months ranges from 65 % to 76 % depending on the death calibration, whereas high isolation (70 %) reduces the risk of a ≥10 000‑case outbreak to about 1 % (for the 50‑death scenario). Higher R₀ values markedly increase large‑outbreak probabilities. The inferred spillover dates range from late January to early March 2026, earlier for higher death calibrations. The authors conclude that, unless rapid, large‑scale public‑health actions comparable to the 2014‑2016 West Africa Ebola response are implemented, the BVD outbreak could become one of the largest Ebola epidemics ever recorded. Limitations include uncertainty in true death counts, R₀ variability, omission of behavior change, immunity buildup, and relapse dynamics. The report also reiterates that the risk to the U.S. population remains low.