The phrase apparently originated in Spain in the 17th century and was ‘loosely applied in England to typhus or any fever involving petechial eruptions.’ During the 17th and 18th centuries, it was thought to be "cousin-germane" to and herald of the bubonic plague, a disease which periodically afflicted the city of London and its environs during the 16th and 17th centuries, most notably during the Great Plague of 1665.