English sweating sickness: what was it?

A disease that killed within hours, often the healthy and well-off, in five English epidemics: 1485, 1508, 1517, 1528 (which spread to Germany and Scandinavia in 1529) and 1551. Then it vanished. A milder 'Picardy sweat' caused 196 local outbreaks in northern France from 1718 to 1861. The cause is unknown; the leading idea is a hantavirus, a rodent-borne virus, partly because chroniclers said outbreaks followed prolonged rain, wet winters and ruined harvests (Heyman et al. 2014, citing Creighton).