This article leaves a lot of stuff, all of it very bad, unsaid. In the seventeenth and eighteenth centuries, plus many preceding ones, it was spread by lice as well as fleas and was one of the greatest killers of humanity. Indeed it was particularly lethal in places, like jails and armies, where people were highly concentrated. As far as jails were concerned, it was known as “goal fever” and killed thousands. It was even worse in armies, having killed whole armies during the Thirty Years’ War. Its greatest slaughter of all probably occurred during Napoleon’s 1812 invasion of Russia where it probably killed about half of his initial army of about 600,000, only about 20,000 of whom survived the whole campaign.
Sorry for the triple post; got distracted.