(Source: PHG 2015-01-30）
Scientists tracking the Ebola virus say it is mutating, as the World Health Organisation (WHO) announces the outbreak has moved into the endgame.
January 2014 saw the first cases of the current Ebola outbreak, which has killed more people than all other known Ebola outbreaks combined. The virus is now thought to be in its second phase with fewer than 100 cases of Ebola reported in West Africa last week.
Earlier this month Broad Institute of MIT and Harvard reported more than 300 genetic changes that separated the current Ebola virus from predecessors. Similarly, genomic analysis is of paramount importance in seeing how the virus is evolving, especially if it is acquiring new mutations that could enhance its infectivity or pathogenicity.
Researchers at the Institut Pasteur in France, who first identified the Ebola outbreak last March, have been tracking mutations in the virus which could make it easier or harder for the virus to jump from person to person. Human geneticist, Dr Anavaz Sukunthabi told the BBC: “We know the virus is changing quite a lot…that’s important for diagnosing (new cases) and for treatment”.
Previous outbreaks have faded out after claiming many fewer lives; generally, Ebola kills human hosts too quickly to spread widely when cases arise from animal transmission in remote African villages. However, Sukuntabhai said that in the current outbreak there have been several cases that don’t have any symptoms; known asymptomatic cases: “These people may be the people who can spread the virus better, but we still don’t know that yet. A virus can change itself to less deadly, but more contagious and that’s something we are afraid of”.
But Professor Jonathon Ball, a virologist at the University of Nottingham said it is unclear whether we are seeing more asymptomatic infections proportionally in the current outbreak compared to previous ones.
As the Ebola virus is analysed, others are analysing how the outbreak has been, and is being, handled and what can be learnt looking forward. Jim Kong Kin, president of the World Bank warned: “We must learn the lessons from the Ebola outbreak because there is no doubt we will be faced with other pandemics in the years to come”.
Meanwhile, the New England Journal of Medicine published promising results from a vaccine trial by Oxford University; no safety problems were reported, although the immune system responses to the vaccine were not as strong as scientists would have liked. With the falling number of cases, new vaccine trials are becoming a considerable challenge.
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