The possible causes, if a supernatural explanation is discarded, are clear (some of which have already been discussed): mass hysteria in a frightening situation, hallucinations caused by herbal remedies, hallucinations caused by the plague, suggestibility, clinical nightmares, and an intense need to lay the blame for the deaths causing such havoc firmly and squarely upon something, anything.
In such cases, there was no need to find the vampire. It was simply a matter of heading straight for the corpse’s burial place and doing what needed to be done. It was also easy enough to find the grave of the plague’s first victim, traditionally assumed to be the vampire responsible for the following deaths.
But in the majority of cases, there was no easy way to tell which of the corpses had turned into a vampire. (In particular, when the obvious corpses had already been dealt with, and the deaths still continued, the living assumed that there were other vampires still walking.) Various methods were practised – methods which certainly exhibit the people’s desperation for a solution rather than their common sense.
Read, for instance, the substantial excerpt below, in which one method of finding a vampire is mentioned. The text is a translation of a letter sent by a cornet in the Austrian Imperial Army, in 1732. The letter was included in Dom Augustin Calmet’s influential work on the subject of revenants in Hungary, Bohemia, Moravia and Silesia, and translated by Montague Summers in his work in the 20th century. The letter is addressed to a near relative of the writer.
"It is your wish, my dear cousin, that I should give you exact details
of what has been happening in Hungary with regard to certain apparitions,
who so often molest and slay people in that part of the world. I am in a position
to afford you this information, for I have been living for some years in those
very districts, and I am naturally of an inquiring disposition. From the time
when I was a mere boy I have heard numbers of stories of ghosts and witches,
but not once in a thousand have I believed one of them; it seems to me that
it is almost impossible to be too careful in the investigation of matters
where it is so easy to be mistaken – or deliberately tricked. However
there are certain facts so well vouched for that one cannot but accept them
as true. As to the apparitions of Hungary this is the usual account. A person
is attached by a great languor and weariness, he loses all appetite, he visibly
wastes and grows thin, and at the end of a week or ten days, may be a fortnight,
he dies without any other symptom save anæmia and emaciation.
"In Hungary they say that a Vampire has attacked him and sucked his blood.
Many of those who fall ill in this way declare that a white spectre is following
them and cleaves to them as close as a shadow. When we were in our Kaloesa-Bacs
quarters in the County of Temesvar [99] two officers of the regiment in which
I was Cornet died from this languor, and several more were attacked and must
have perished had not a Corporal of our regiment put a stop to these maladies
by resorting to the remedial ceremonies which are practised by the local people.
These are very unusual, and although they are considered an infallible cure
I cannot remember even to have seen these in any Rituale.