What makes this Ebola outbreak different

Ebola cases are rising again in central Africa. This time, the outbreak is being driven by a virus for which there is no approved vaccine.

Health authorities are racing to contain the spread, but delayed detection, limited testing capacity and difficult conditions on the ground are complicating the response.

Simon Clarke, who specializes in infectious diseases, told DW what is different about this outbreak, why existing vaccines don't apply and what it will take to bring it under control.