Yesterday was the anniversary of the London fire of 1666. A century or two earlier were the plagues where there exist more than one account of people saying "lights appeared in the sky" or "great comets with trails of mist" occurred before outbreaks. Johannes Nohl wrote a book chronicles of the plague where he goes into these comets. Nohl makes it a point to draw a connection between comets and the appearance of plagues.

When in sun and moonlight a beautiful rainbow and a fiery beam were seen hovering above the church of St. Stephanie, which was followed by a violent epidemic in Austria, Swabia, Augsberg, Wuetemberg, Nuremburg, and other places, carrying off human beings and cattle.

Then you have Walter George Bell, an English Historian, reporting from 1664.

Late into dark December nights of the year 1664 London citizens sat up to watch a new blazing star, with "mighty talk" thereupon. King Charles II and his Queen gazed out of the windows at Whitehall...In March there came into the heavens a yet brighter comet visible two hours after midnight, and so continuing till daylight. With such ominous portents the Great Plague in London was ushered in.

After looking at some of this information about the plagues I am scratching my head. Bubonic plague needs a carrier like fleas or rats to spread and is not contagious. However reports from the time show that there was no real rat problem. But what do I know I am not alive then nor am I the one manipulating history.