The Sweating Sickness is a Tortallan epidemic. The main symptoms of the sickness seem to be persistent coughing and a very high fever which eventually leads to the death of the sick person.
Another time was in March of 431 HE. This outbreak of the sickness wasn't of natural causes, however, as Duke Roger sent it to harm the royal family. The first to fall ill were people living in the city of Corus. This outbreak was tragically distinct from others: it drained the healers trying to help the sick people. Thus there was barely a healer left who could still work, when the sickness began to hit the Royal Palace.
So many of the palace inhabitants fell ill, including pages, squires and their teachers, that the pages' lessons were suspended during the outbreak.
Among the sick were Queen Lianne, the Lord Provost and Duke Gareth. Francis of Nond, a page, was one of the first to die of the sickness. Another page to fall ill was Raoul of Goldenlake, but he got better and fully recovered from the sickness. Jonathan of Conté was one of the last to fall sick, once the healers were already drained of their magic. He was eventually healed by Alanna of Trebond. The Queen became better but did never fully recover from the sickness as it left her with very frail health and Duke Roger used further magic to harm Lianne.