This episode covers the 1928 Nobel Prize in Physiology or Medicine, which was awarded to Charles Jules Henri Nicolle. The Nobel Assembly at the Karolinska Institute chose to give Nicolle the award “for his work on typhus”. Topics include some history of typhus epidemics, the work Nicolle did to show lice transmit typhus, and the unusual biology of Rickettsia prowazekii, the bacterium that causes typhus.