Health workers in Uganda carry the body of a 3-year-old suspected Ebola victim of the 2022 Ebola outbreak for a Safe and Dignified Burial, while community members look on. Credit: Luke Dray/Stringer/Getty Images News
A critical four-week detection gap allowed a rare Ebola strain to spread through eastern Democratic Republic of the Congo (DRC) before health authorities confirmed the outbreak.
The outbreak, caused by the Bundibugyo strain of Ebola virus, was officially declared by DRC authorities on 15 May after laboratory confirmation in Kinshasa. The World Health Organization (WHO) says the presumed index case, a health worker in Bunia, Ituri province, first developed symptoms on 25 April and later died.
By the time the outbreak was confirmed, infections had already spread across at least nine health zones in eastern DRC and into neighbouring Uganda, where authorities reported a fatal case in Kampala.
In a Disease Outbreak News report, WHO referred to a “critical four-week detection gap” between the onset of symptoms in the presumed index case and laboratory confirmation of the outbreak, so that transmission was underway before surveillance systems were fully activated.
The infection and deaths of four health care workers within four days at Mongbwalu General Referral Hospital also suggested significant breaches in infection prevention and control measures, highlighting the risks of delayed recognition in health care settings.
WHO says early laboratory testing also contributed to delays in confirming the outbreak. Initial samples reportedly tested negative before further analysis at the National Institute of Biomedical Research in Kinshasa confirmed Bundibugyo virus in eight of 13 samples.
The delayed confirmation also exposed important diagnostic limitations. Describing the outbreak, infectious disease ecologist, John Drake, of the University of Georgia, in the United States, noted that regional laboratories in Bunia initially tested samples using GeneXpert assays designed to detect the Zaire strain of Ebola virus, which was responsible for previous outbreaks in DRC, and the 2014 West Africa epidemic.
The current outbreak, however, is caused by the much rarer Bundibugyo strain, first identified in Uganda in 2007. The outbreak highlights how surveillance systems calibrated for the most common Ebola strain may not quickly identify rarer species.
Médecins Sans Frontières says it received alerts on 9 and 10 May about an unusual increase in deaths linked to suspected viral haemorrhagic fever in Mongbwalu health zone, north-west of Bunia. Working alongside Congolese health authorities, MSF teams found that 55 people had died since the beginning of April.
“The number of cases and deaths we are seeing in such a short timeframe, combined with the spread across several health zones and now across the border, is extremely concerning,” says Trish Newport, MSF Emergency Programme Manager.
In a statement accompanying its declaration of a Public Health Emergency of International Concern, WHO described “significant uncertainties” around the true number of infections, and the geographic extent of transmission.
WHO added that clusters of unexplained deaths, syndromic surveillance reports, and the high positivity rate among initial samples “all point towards a potentially much larger outbreak than what is currently being detected and reported”.
WHO says initial lab testing also contributed to delays in confirming the outbreak. Initial samples reportedly tested negative before further analysis at the National Institute of Biomedical Research in Kinshasa confirmed Bundibugyo virus in eight of 13 samples.
The Africa Centres for Disease Control and Prevention (Africa CDC) further warned that the outbreak is unfolding in an area marked by “high population mobility, insecurity and intense cross-border connectivity”, conditions that increase the risk of wider regional spread.
Africa CDC has called coordination meetings involving DRC, Uganda, South Sudan, WHO and other partners, focused on cross-border surveillance, laboratory sequencing, infection prevention and contact tracing.
“This outbreak reminds us that an outbreak anywhere is a threat everywhere,” said Africa CDC Director-General Jean Kaseya. “Early detection, transparent information sharing and coordinated regional action are essential to stopping Ebola before it spreads further.”
“Working closely with national authorities and partners, we are mobilising swiftly, deploying additional expertise and resources to halt the spread of the virus, protect and save lives,” said Mohamed Janabi, WHO Regional Director for Africa.
Unlike the Zaire strain, there is currently no licensed vaccine or approved treatment specifically for Bundibugyo Ebola.
