Rachel

“Here also I ought to leave a further remark for the use of posterity, concerning the manner of people’s infecting one another; namely, that it was not the sick people only from whom the plague was immediately received by others that were sound, but the well. To explain myself: by the sick people I mean those who were known to be sick, had taken their beds, had been under cure, or had swellings and tumours upon them, and the like; these everybody could beware of; they were either in their beds or in such condition as could not be concealed.

By the well I mean such as had received the contagion, and had it really upon them, and in their blood, yet did not show the consequences of it in their countenances: nay, even were not sensible of it themselves, as many were not for several days. These breathed death in every place, and upon everybody who came near them; nay, their very clothes retained the infection, their hands would infect the things they touched, especially if they were warm and sweaty, and they were generally apt to sweat too.”
― DEFOE, DANIEL