Caption:
Epidemic Typhus or Gaol Fever, caused by the organism Rickettsia prowazeki, is spread by lice. Here a peasant woman in the Spanish Pyrenees is removing lice, the vector for the disease, from her child's head as the family takes a rest on their journey. Tinted lithograph from "Nouvelles Suite de Costumes des Pyrenees" (Paris, c1840). (Photo by: Universal History Archive/UIG via Getty Images)