Invisible Killers

The history and impact of influenza is explored, from its ability to constantly evolve to the constant threat it poses and the complex science behind it.

Recalling the ravages of smallpox through the ages and its ultimate eradication at the dawn of the 1980s, after which fears grew of the disease being turned into a bioterror weapon.

An examination of Ebola, which has become one of the world's deadliest viruses, looks back at the devastating 2014 West African outbreak.