Despite mutating, the ebola virus has not evolved to become deadlier since the first outbreak 40 years ago, scientists say. The findings suggest that the much higher death toll during the current outbreak, with the figure at nearly 10,500, is not due to mutations making the virus more deadly or more virulent.
Researchers from The University of Manchester used cutting edge computer analysis to demonstrate that while a high number of genetic changes have been recorded in the virus, it has not changed at a functional level to become more or less virulent. “Using data from every outbreak since 1976 we were able to highlight what changes there had been in the RNA of the virus and then using specially developed tools predict the consequences of those changes,” said Professor Simon Lovell from the Faculty of Life Sciences.
“What we found was that whilst Ebola is mutating, it isn’t evolving to the point of adapting to become more or less virulent. “The function of the virus has remained the same over the past four decades which really surprised us. Unfortunately this does mean the Ebola virus that has now emerged on several occasions since the 1970s will very probably do so again,” Lovell said.
Professor David Robertson said the findings, published in the journal Virology, can be seen as good news. “The fact that Ebola isn’t changing in a way that effects the virulence of the disease means that vaccines and treatments developed during this current outbreak have a very high chance of being effective against future outbreaks,” said Robertson. “It also means that methods to successfully tackle the virus should work again, so hopefully in the future an outbreak can be stopped from spreading at a much earlier stage,” he said.
The researchers also stress that, counter-intuitively, analysis is needed to identify when a virus becomes less potent. This is because infected individuals could potentially infect more people if they did not progress to severe illness. The deadly nature of Ebola means the symptoms can be identified at a relatively early stage and those who had been in contact with the patient during the infectious stage readily identified by contact tracing. If it becomes less deadly then it may take longer to spot those symptoms, if they can be spotted at all, or for the person to become ill increasing the chance of spreading the virus.
An attenuated virus, although less deadly on an individual basis, could spread widely and thus ultimately cause many more deaths. The Ebola outbreak that began last year in West Africa has infected almost 25,000 people and killed nearly 10,500. PTI
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