Study of Liberia Ebola flare-up shows need for longer vigilance

A study of a cluster of Ebola cases that appeared in Liberia last year, months after the country was declared Ebola-free, has found that the virus re-emerged after lying dormant in a female survivor. The results suggest Liberia and the other African countries at the centre of the outbreak should maintain high levels of vigilance for longer than thought to contain any future flare-ups of the deadly haemorrhagic fever. World Health Organization data show West Africa's Ebola epidemic killed more than 11,300 people and infected some 28,600 as it swept through Guinea, Sierra Leone and Liberia from 2013 in the world's worst outbreak of the disease.