(from About Ghosts: A Useful Handbook by Jan Olandese )
There is a class of ghost we might think of as contagious. They produce a kind of infectious malaise, and sometimes more. These may be present when you visit a place and something tells you to leave right away. You often ignore the feeling, but the longer you hang around, the worse it gets.
I remember visiting a house like that. A friend was house-sitting there and had invited us over. It was a very attractive place. It belonged to an artist who had decorated it beautifully with original pieces. What was not to like?
Good question. All I can tell you is that everyone who ever visited there had this reaction: first five or ten minutes were fine. Then one would begin to feel edgy, restless. A little longer, one became nervous. And soon thereafter, one felt compelled to leave.
The friend who stayed there was not a dog lover, but was actually happy to have the owners’ large dog in the house with him. He told me he was terrified much of the time he was there.
Houses like this or entities like this – take your pick – seem steeped in some kind of negative energy field. It is not comfortable to be within or even near it.
A ghost story with another, more literal take on the contagion question is Caterpillars, by E. F. Benson. In it, the narrator visits friends at an Italian villa. Another house guest is there at the time, one who is careless, opinionated and somewhat loud. He declares early on that anyone who believes in ghosts must be an ass.
In the story, the narrator describes how lovely the house and surroundings are, but also that the moment he entered the place, something felt quite wrong to him.
When rooms are assigned, the hostess steers them away from one room, and goes rather to excess in explaining why. In the course of the story, contagion in the form of ugly caterpillars which seem bathed in a peculiar gray light take over the corridors and go from the unused room eventually to the room of the guest who has no time for ghosts. Later, we learn that he dies of cancer, and the caterpillars did indeed resemble tumors with crab-like claws.
Cancer, in this story may have reflected beliefs of the time (it was written in 1912) about cancer and contagion. Perhaps it seemed logical to assume that it might spread from a place at which someone had succumbed of the disease. Given the level of knowledge about cancer in those days, the story may not have seemed as politically incorrect as it does now.
No one “deserves” to have cancer. But if we think of the cancer in this story allegorically, as a negative energy attracted to the character because of his words or behavior, it makes more sense (and fits the cautionary model). It’s a great illustration of the contagious element in some ghosts and hauntings.
Another aspect of ghost contagion is the often told story of people who live in a haunted dwelling, then move, but only to find that the ghost(s) followed them. The spirits become attached to the individuals. Whether you wish to classify the entities as paranormal or psychological, they are still quite overwhelming, frightening and difficult for those so affected.