In the early modern period, a wide variety of fevers and other ailments were called “sweating sickness” or simply “the sweating sickness.” Some people suffered from them while others did not. This expression probably derived from two separate diseases that began to circulate in England around 1480, one that caused severe muscle pain among lower-class laborers and another that developed among upper-class women who spent much time outdoors during particularly hot summers. As with most infections at the time, doctors ascribed all manner of evils to these illnesses: they could be brought on by bad air or contaminated food; if left untreated they would lead to insanity, paralysis, death—and even demonic possession. The number of deaths attributed to this disease was staggering: some 5 percent of Londoners died every year between 1583 and 1603 (Klein 2007), putting it second only to bubonic plague as a cause of death in medieval England (Desmond 2008).
The lesser fever spread quickly through Europe at first but became less virulent after about 150 years because its vector had been eliminated (Salska et al., 1996); consequently fewer people contracted it annually thereafter. It has often been assumed that this lesser disease was actually the same illness known as typhus febris which plagued European armies during centuries leading up to World War I (see Chapter 2) until World War II when an effective antiserum against typhus fever helped end epidemics once again (Mendelso