The Journal of the Norwegian Medical Association recently published an experimental study on the protective effect of garlic against vampires. Rather surprisingly, this study showed that garlic seems to have an attractive force on leeches (and probably also on vampires).
Leeches are used in microsurgery to prevent harmful swellings
in replanted body parts. Sometimes however, the leeches refuse
to do their job properly. To stimulate the leeches' appetite
several remedies have been used, such as immersing them in
strong beer before application or smearing soured cream
on the skin. The present study was designed to evaluate the
effect of these remedies (ale, garlic, and soured cream). It was published in the BMJ (British Medical Journal) 1994; 309: 1689.
Differences in willingness to bite were measured by median
time from application on Hogne's forearm to biting him. Some
leeches did not bite within the predefined time limit of 300s,
but as the study was run according to the intention-to-bite
principle, these incidences were registered with a time
interval of 301s in the statistical analysis.
Six leeches were dipped briefly in one of two different types of beer (Guinness Stout or Hansa Bock) or in plain water (control) before being placed on the forearms. Each leech was, in random order, exposed three times to each liquid. As serotonin probably is involved in controlling feeding behaviour, we also measured the serotonin content of both beers (high-pressure liquid chromatography).
After having been exposed to beer, some of the leeches changed
behaviour, swaying their forebodies, losing grip or falling on
their backs. Leeches dipped in Guinness bit after 187s, those
dipped in Hansa after 136s, and controls after 92s. The
serotonin content was low, and similar for the two
beers (0.1 ug/ml).
After having completed the first part of the study the leeches became lazy, their scientific enthusiasm diminished. Discipline failed, appointments were forgotten, some even ran away on their own.
In the next study part six other leeches were therefore used. This time the left forearm was either smeared with soured
cream or not prepared at all. Leeches exposed to soured cream
were often seen sucking frantically on the wall of their
container after they had been on the arm. While on the
cream-smeared arm however they bit no sooner than the
The other forearm was smeared with garlic. Two leeches placed on this arm started to wriggle and crawl without assuming the sucking position. They were placed in water, but their condition deteriorated. When placed on a bare arm they tried to initiate feeding, but did not manage to co-ordinate the process. Both died 2-3 hours after the exposure to garlic. For ethical reasons the garlic arm was abandoned at this point.
We believe this to be the first study showing lethal effect of
garlic by skin absorption. Garlic has a definite force of attraction
on leeches, but further research into this fatal attraction
can only be performed by in-depth qualitative methods.
Let this study be a reminder of how medical beliefs may stand uncontradicted for decades. We should never forget the necessity of critical research on commonly accepted medical truths.
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