New Light on the Black Death: The Viral and Cosmic Connection

Rhawn Joseph, Ph.D., co-authoring researcher with Wickramasinghe in the book Biology Cosmology, Astrobiology, and the Origins and Evolution of Life [3], tells us:

Ancient Chinese astronomers chronicled numerous episodes where comets preceded plague and disaster. Meticulous observations were compiled in 300 B.C. in a textbook known as the "Mawangdui Silk." It details 29 different cometary forms and the various disasters associated with them, dating as far back as 1500 B.C

Joseph points out that medieval Europe and colonial America are areas where comets were observed to coincide with plagues and disease, adding that Comet Encke, the likely origin of the Tunguska impactor and the 1918 Flu epidemic, also coincide.  link