The death toll from the Ebola outbreak in West Africa may be higher than reported, the World Health Organization (WHO) Spokesperson says.

Gregory Hartl told Patrick Maigua that one of the big challenges in this outbreak was tracking all the cases. A lot of cases may have not been reported or come through the health system.

So far WHO has recorded 728 deaths in Guinea, Liberia and Sierra Leone from the deadly disease. One death has been recorded in Nigeria.

Public emergencies have been declared in Liberia and Sierra Leone.

There is growing concern that the virus could spread via air passengers leaving the affected countries.

Mr Hartl started by telling Patrick Maigua about the difficulties in tracking all the cases.

Duration:4'44"