An Ebola outbreak in Guinea has killed nine people, while 18 had been reported sick at the close of last week. Science correspondent Kai Kupferschmidt writes it is not only the trauma of the epidemic that struck the country between 2013 and 2016 that has persisted, but also, in significant likelihood, the virus behind the last outbreak, in the body of a survivor. Genomic analyses, Kupferschmidt reports, show that the virus in the present outbreak hardly differs from the strain reported 5-6 years ago.
The Ebola virus is known to stay in the system for a long time, but scientists are baffled that it could possibly survive for so long. What has also foxed researchers is that the virus hasn’t mutated significantly in such a long duration—typically, RNA viruses (Ebola belongs to this group) have high mutation rates.
High mutation, the thumb rule is, helps the virus to survive longer by bringing down virulence. Against this backdrop, the present case is particularly worrying.
While it hasn’t been scientifically established that the virus stayed dormant in an infected person over 5-6 years—an alternative scenario could be a chain of human-to-human transmission over the years that has gone unreported—the likelihood of this is low, especially given the high visibility of the disease.
The high probability of the virus surviving in humans for such long periods now poses both challenges and opportunities. While—even if this long dormancy is not confirmed—the present instance means that stigmatisation of survivors could become a challenge, the relatively low mutation rate could allow for targeting the virus for research on antiviral development, since mutations could have a negative impact on drug/vaccine efficacy.