Ebola detectives at work in Liberia

There have not been any new cases of Ebola in Liberia for more than a week - and the treatment units are mostly empty.

But, in a country where Ebola has claimed at least 4,000 lives, the case need for vigilance remains.

BBC Africa correspondent Andrew Harding has been out with Liberia's ''Ebola detectives'', as they attempt to bring the caseload down to zero.