Clinical Characteristics of Patients Infected with Bundibugyo Virus, DRC 2026

To the Editor: The clinical characterization of Bundibugyo virus disease (BVD), caused by Bundibugyo virus, a species of orthoebolavirus, is less well described than infection with more frequently encountered filovirus species. 1 We report here signs and symptoms and basic laboratory data from the current 2026 BVD outbreak in the Democratic Republic of Congo (DRC).Ethics approval for this study was obtained from the ethical review committee of the University of Kinshasa.Among 2351 recorded cases in the individuallevel database for BVD between May 3 and June 8, 2026, a total of 505 patients (21.5%) had a laboratory-confirmed case of BVD (as determined by Altona Diagnostics and RADIONE polymerasechain-reaction [PCR] tests 2 ), and 635 patients (27.0%) with suspected BVD tested negative.The remaining patients were untested, had pending results, or had results that remained classified as being suspected or probable.Among the 505 patients with laboratory-confirmed BVD who had records in the database, 95 (18.8%) had died by the data-cutoff date, as compared with 65 of the 635 patients (10.2%) who had tested negative.This finding cannot be interpreted as the case fatality rate owing to limited data on final outcome and unknown denominators.Patients with confirmed BVD were demographically similar to those who tested negative; in both groups, the majority of patients were adults 20 and 39 years of age, and there were slightly more female patients than male patients (Fig. S1 in the Supplementary Appendix, available with the full text of this letter at NEJM.org).Since the declaration of the outbreak on May 15, 2026, the number of positive cases has increased, despite test positivity decreasing from roughly 70 to 80% in early May to approximately 40% by early June.Signs and symptoms at presentation were recorded for 405 patients with confirmed BVD and for 516 patients who tested negative (Table 1).In