Reconstruction of outbreak, which has killed more that 11,000 people, found virus might have been contained had Ebola been diagnosed one month earlier.
Scientists have analysed the genetic code of Ebola viruses from patients across west Africa and pieced together the evolution of the worst ever outbreak of the killer disease.
Experts from Public Health England at Porton Down in Britain, the World Health Organisation (WHO), and other leading labs, used genetic material from 179 Ebola samples to reconstruct the spread of the virus from Guinea into surrounding countries last year.
The study found that the initial outbreak had been dying out in Guinea in early 2014 and might have been contained had the international community diagnosed Ebola just one month earlier than it did. The outbreak has so far recorded 27,000 cases and killed more than 11,000 people.
|A team of heath workers in Sierra Leone looking for those exhibiting symptoms of the disease as well as providing information and education about the virus. Photograph: Michael Duff/AP|
“The initial containment was nearly successful. If we’d been out there not at the end of March, but in February, maybe this would never have happened,” said Miles Carroll, head of microbiology research at Public Health England. “We could have stopped a lot of health workers and patients from becoming infected.”
Many researchers trace the origins of the Ebola outbreak back to a two-year-old boy called Emile, who died from the infection a few days after Christmas, in 2013. The boy may have contracted the virus from fruit bats that were roosting in trees near Meliandou, a village in southern Guinea.
The latest analysis, reported in Nature, supports that account, but does not prove it. The virus leapt from an infected animal into a human some time between December 2013 and February 2014, the study found.
Doctors at Médecins Sans Frontières in Guéckédou, a town in southern Guinea near the borders of Sierra Leone and Liberia, sent the first samples of what turned out to be Ebola to labs in Hamburg and Lyon in March 2014. The labs confirmed the identity of the virus and alerted the WHO, which dispatched a rapid response unit called the European Mobile Laboratory to the scene. Tens of scientists travelled with diagnostic equipment to Guinea’s capital, Conakry, and onwards in four-by-fours to Guéckédou. The unit they set up ensured patients with Ebola were not sent to the main hospital, where the infection would easily spread to health workers and patients.
|Ebola crisis in Liberia brings rumours, hygiene lessons and hunger|
According to the study in Nature, the initial outbreak grew around Guéckédou, Macenta and Kissidougou in Guinea in March 2014. By the end of May a new strain of the virus had been carried to Sierra Leone, and also into Liberia. The virus spread rapidly in those countries, before being carried back into Guinea from June 2014 onwards. This second wave was far worse than the first outbreak. In the autumn, the virus crossed twice from Guinea into Mali, from Beyla district in October and from the Siguiri district one month later.
Beyond the light it casts on the way Ebola spread, Carroll said the study shows how, with present technology, we cannot predict where the next outbreak will occur. “What we need is an early warning system that uses real time genetic sequencing, and an effective and rapid response plan,” he said.
• This article was amended on 18 June 2015. An earlier version referred to DNA, but Ebola’s genetic material is RNA. The piece also referred to the Health Protection Agency where Public Health England was meant.