In 1976, a group of health workers took a pair of film cameras to what was then known as Zaire and documented their discovery of a new, deadly virus.

Today we know that virus as Ebola.

A 27-year-old Belgian microbiologist named Peter Piot and his colleagues were the first to scientifically identify the Ebola virus.

The Wall Street Journal met Dr. Piot recently and was given access to rare archival footage that chronicled the team’s trip nearly four decades ago.

Dr. Piot described how the medical mystery tour in Zaire—what is now the Democratic Republic of the Congo—unfolded.