This year’s Ebola outbreak in Guinea was probably caused by someone who was originally infected during the 2014-16 west African eruption, according to new research with serious implications about the longevity of one of the world’s most deadly pathogens.
The latest outbreak has killed nine people this year, and the earlier outbreak killed more than 11,000 people in Liberia, Sierra Leone and Guinea.
Genetic sequencing revealed that samples from the current outbreak are closely related to strains from August 2014, according to the report, which was released on Friday.
It is highly likely that a person who contracted the virus previously and survived subsequently passed it on to someone else, the research concluded, although it cautioned that “these results are still preliminary, and more sequencing and analyses are under way”.
“This is truly mind-blowing,” Dr Angela Rasmussen, a virologist at Georgetown University in Washington DC, wrote on Twitter. “The implications for controlling Ebola are extremely worrisome.”
Researchers had previously assumed the latest outbreak in Guinea, which was declared on February 14, was sparked by transmission from an animal such as a bat. Both outbreaks began in the same region, near the border with Liberia and Sierra Leone.
The highly contagious disease is spread through contact with bodily fluids. It causes haemorrhagic fever and severe vomiting, diarrhoea and bleeding.
It is rare for survivors to transmit the disease, but the virus is able to hide within the human body in places where the immune system cannot reach it, including the eye, the testes and the central nervous system. Scientists previously found that the virus could persist in a patient for 500 days, and sexual transmission of the disease has been known.
The new research suggests it can persist for four or five times as long.
The World Health Organization kicked off a vaccination drive in the region at the heart of the outbreak on February 23. But the new research has sparked calls for more widespread vaccination in west and central Africa, where jabs made by Johnson & Johnson and Merck are generally only deployed in response to outbreaks.
The findings suggest “we need to step up our efforts to provide Ebola vaccines to people in affected communities, including survivors”, Rasmussen said on Twitter.
The research was conducted by Guinea’s healthy ministry, the Institut Pasteur in Senegal, the University of Nebraska Medical Center in the US, the company PraesensBio and the University of Edinburgh.
The virus could have been passed on via sex, the researchers suggested.
Dr Christian Happi, head of the African Center of Excellence for Genomics of Infectious Diseases, called the results of the study “stunning” but warned that the researchers may have jumped the gun by pointing to possible sexual transmission without presenting any evidence.
“I think it’s a bit sloppy to make such statements . . . it would have been best to say we don’t know the origin of this virus,” he said, noting that many Ebola survivors suffer stigmatisation, including being shunned by their communities.
Like other sub-Saharan countries, Guinea has not been greatly affected by the coronavirus pandemic, recording just 102 confirmed deaths out of 17,591 cases over the past year.