Updated May 19, 2026
Health officials are alarmed by an outbreak of the Bundibugyo strain of Ebola affecting parts of the Democratic Republic of the Congo and Uganda. As of May 19, suspected cases have risen sharply to more than 500, with at least 131 reported deaths. One American doctor working with an aid group in Congo has tested positive, and several other Americans are believed to have been exposed.
The virus driving this outbreak is Bundibugyo virus, a less common species of orthoebolavirus. This is only the third known outbreak caused by Bundibugyo. Unlike the more frequent Zaire (Ebola) virus, Bundibugyo is not covered by the only approved Ebola vaccine and treatments currently available.
Approved vaccines and therapeutics target the Zaire ebolavirus. Because different ebolavirus species have distinct genetics, vaccines and treatments developed for one species do not reliably protect against others. Companies and researchers have explored whether Zaire-targeted vaccines might offer some cross-protection, but data are limited, largely preclinical, and do not support use of existing licensed products against Bundibugyo.
Before this event, Bundibugyo virus had caused two smaller outbreaks: in Uganda in 2007 (about 149 cases, 37 deaths) and in the DRC in 2012 (about 57 cases, 29 deaths). Because Bundibugyo outbreaks have been rare, there is less clinical and epidemiologic data on its behavior compared with the Zaire strain, which has caused many more and larger outbreaks since 1976.
Bundibugyo virus disease is severe and often fatal. The virus spreads person-to-person through direct contact with the bodily fluids of someone who is ill or has died from the disease. Early symptoms are nonspecific and can resemble other infections: fever, fatigue, muscle pain, headache and sore throat. These may progress to vomiting, diarrhea, abdominal pain, rash, organ dysfunction and, less frequently, internal or external bleeding.
Based on past outbreaks, the observed fatality rate for Bundibugyo virus disease has been roughly 30–50%, lower than the highest reported fatality rates for Zaire ebolavirus but nevertheless substantial.
There are currently no licensed vaccines or specific antiviral treatments for Bundibugyo virus. Several candidate vaccines are in development for non‑Zaire ebolaviruses, but none are immediately available for deployment. Supportive care remains the cornerstone of treatment: early intensive care, rehydration, and symptomatic management can improve survival. Public health measures—rapid case identification, isolation, contact tracing, safe burial practices and protective equipment for health workers—are critical to limit spread.
Health authorities urge people in affected areas to seek care quickly if they develop symptoms and to follow public health guidance. International and local health agencies are monitoring the situation and coordinating response efforts.