WHO: Ebola taking 'heavy toll' on health staff

An "unprecedented" number of doctors and nurses have been infected with Ebola virus in west Africa, according to the World Health Organization.

More than 240 health care workers have developed the disease in West Africa, and more than 120 have died.

Meanwhile, doctors in London continue to treat 29-year-old William Pooley who contracted Ebola in Sierra Leone.

Jon Brain reports.