Large swathes of the West African population may be immune to the deadly Ebola virus, ravaging the region. The current outbreak, the worst on record since the virus was discovered in 1976, has claimed the lives of 4,493 people, infecting 8,997, the World Health Organisation said yesterday. But a team of scientists in the US believe the Ebola virus may be silently immunising a significant portion of the population, who never fall ill or infect others, protecting them from future infection. These people will never show the tell-take signs of the disease, the high fever, headaches and flu-like symptoms. They...