Typhus

Typhus, a contagious disease with a high mortality rate, periodically struck in epidemic form. Nicolle discovered that the body louse was responsible for spreading typhus by biting infected individuals and then others. This finding laid the groundwork for controlling typhus by removing body lice.
 Charles-Jean-Henri Nicolle France 1909 Typhus

Typhus, a contagious disease with a high mortality rate, periodically struck in epidemic form. Nicolle discovered that the body louse was responsible for spreading typhus by biting infected individuals and then others. This finding laid the groundwork for controlling typhus by removing body lice.