A new study in Nature Medicine says eastern DRC’s deadly disease outbreak began with a fresh animal-to-human spillover, then spread mainly from person to person. More than 2,000 people have died, and the virus has been recorded in 4,449 cases across the Democratic Republic of the Congo.
Nature Medicine study on eastern DRC
Researchers from the DRC, Uganda, Belgium and other countries analysed virus samples from 22 patients in the DRC and Uganda. The report says the strain was genetically distinct from previous Bundibugyo Ebola viruses seen in 2007 and 2012, and genetic sequencing later showed the virus had begun circulating in February, even though the outbreak was formally declared on May 15.
Krutika Kuppalli said, “What the genomic data suggest is that the current outbreak began with a new ‘zoonotic spillover’ event – meaning the virus likely crossed independently from an animal reservoir into a person – rather than resulting from continued circulation or re-emergence of virus from a previous human outbreak”. She added, “After that initial spillover, the outbreak has been driven predominantly by human-to-human transmission”.
WHO warns on Wednesday
On Wednesday, the World Health Organization said the current Bundibugyo strain is spreading faster than health authorities can contain it. Tedros Adhanom Ghebreyesus said that “at its current pace, the current Ebola outbreak is on track to eclipse the West African outbreak of 2014 to 2016”, which killed at least 11,300 people in 28,600 cases and involved the Zaire strain.
The current strain is different. Health officials in the region say the outbreak is being driven by Bundibugyo Ebola, and no vaccine has yet been developed for that strain. The vaccine developed for Zaire does not work for the current strain, which narrows the tools available while transmission continues in eastern DRC.
Six months or 12 months
Dr Abdirahman Mahamud said the agency’s moderate projection has the outbreak peaking within six months. Under a more severe scenario, he said, the outbreak could stretch on for nine to 12 months. Kaja Abbas said, “Beyond the zoonotic spillover event from animals to humans, it is the human-to-human transmission dynamics of the Bundibugyo virus that make it dangerous”.
What remains in focus is the animal source behind the spillover, which the study did not specify. Until that reservoir is identified, the immediate operational challenge in eastern DRC is not just stopping spread between people, but narrowing the chain that started it.
