Liberia is now free of Ebola after no new cases were reported in 42 days, twice the maximum incubation period for the deadly disease, the World Health Organisation (WHO) has announced.

However, new cases emerged this week in neighbouring Sierra Leone and in Guinea, the other two countries hit hardest by the worst Ebola outbreak in history. Each country recorded nine new cases in the week ending May 3, according to the WHO's latest situation report. Officials said they are cautious about openly celebrating the end of Ebola in Liberia, given the continued presence of the disease in the region.