The Picardy sweat was an infectious disease of unknown cause. It appeared in the northern French province of Picardy in 1718. Between 1718 and 1874, 194 epidemics of the Picardy sweat were recorded. The last extensive outbreak was in 1906, which a French commission attributed to fleas from field mice. A subsequent case was diagnosed in 1918 in a soldier in Picardy.
It was named suette des Picards in France, and picard'scher Schweiß or picard'sches Schweissfieber in Germany. There were several longer descriptions of the disease.
The disease was similar to the English sweat but differed in some symptoms and in its course and mortality rate. Some of the symptoms were high fever, rash, and bleeding from the nose. Many victims died within two days.