Companion Reaction Syndrome (CRS) was a destructive psychological condition that came as a result of first contact with the Taelons. The arrival of the alien species challenged the belief systems of millions across the planet Earth which led to an abberant condition which ranged from mild depression and confusion to mass suicides that tended to only manifest amongst groups of people rather than individuals. It was believed that the condition had passed until a number of mass deaths occured in a small Amish community which was reported to William Boone by Amish doctor Elijah Good. (Episode: To Float Like a Butterfly)