The Ebola outbreak in eastern Democratic Republic of Congo likely began nearly two months before it was detected and is expected to keep growing, the World Health Organization said on Wednesday.
The outbreak involves the rare Bundibugyo strain of Ebola, for which there is currently no approved vaccine. It was officially declared last Friday, but WHO officials said the virus may have been spreading silently for weeks in a densely populated and conflict-hit area, making contact tracing and isolation far more difficult.
“Investigations are ongoing to ascertain when and where exactly this outbreak started,” Anais Legand, a WHO technical officer for viral threats, told reporters in Geneva. “Given the scale, we are thinking that it has started probably a couple of months ago.”
The WHO had earlier warned of a “critical four-week detection gap” between the first known symptoms and laboratory confirmation of the outbreak.
Six hundred suspected cases and 139 suspected deaths have been recorded so far, WHO Director-General Tedros Adhanom Ghebreyesus said. Fifty-one cases have been confirmed by laboratory testing in Congo, while two additional cases have been confirmed in neighbouring Uganda.
Tedros said a WHO Emergency Committee had confirmed the outbreak as a public health emergency of international concern, but not a pandemic emergency. He said the risk was considered high at national and regional levels, but low globally.
The Bundibugyo strain has an average fatality rate of about 40 percent, according to the WHO. Unlike the more common Zaire strain of Ebola, there are no approved virus-specific vaccines or treatments for Bundibugyo, and testing capacity remains limited.
WHO experts said two possible vaccines are being considered, but they may take three to nine months to develop.
The agency’s emergencies chief, Chikwe Ihekweazu, said the immediate priority was to identify all active chains of transmission.
“Our absolute priority now is to identify all the existing chains of transmission,” he said, adding that this would help define the true scale of the outbreak and allow responders to provide care.
Health officials suspect the first known death occurred on April 20 and may have been followed by a super-spreading event, either at a funeral or inside a healthcare facility.
The outbreak has also exposed shortages among first responders in eastern Congo. Medical teams say they lack basic supplies, including painkillers, face masks and motorcycles needed to trace contacts in remote areas.
Congo has dealt with 16 previous Ebola outbreaks, including the 2018-2020 Zaire strain outbreak in eastern DRC, which killed nearly 2,300 people and became the second-deadliest Ebola outbreak ever recorded.
An American doctor working in Congo is among the confirmed cases and has been transferred to Germany for treatment. His wife and four children, who had also been in Congo, are being taken to an isolation ward at the same hospital, Germany’s health ministry said.
A second U.S. doctor who had contact with an Ebola patient is being transferred from Uganda to a hospital in Prague, Czech officials said.
The United States said it had mobilised an initial $13 million for the response and would support the opening of 50 Ebola treatment clinics. The Africa Centres for Disease Control and Prevention said South Africa had pledged $2.5 million to support response efforts.
Some health experts have warned that delays in detecting the outbreak may point to weakening preparedness after funding cuts by the U.S. and other major donors to global health programmes.
Tedros said it was still too early to determine whether funding reductions in Congo or at the WHO contributed to the delay in detecting or responding to the outbreak.