Obviously, humans cannot literally transform into a wolf whenever a full moon rises but there are two well documented medical conditions that could convince people otherwise. The first is hypertrichosis, which is characterised by excessive hair growth. The patient’s entire body can be covered in a thick layer of hair, affecting women as often as men. The condition has a genetic cause but can also be acquired later in life as a symptom of other conditions including cancer and anorexia. The hair of a person with hypertrichosis is thicker than on a gorilla, which makes the scientists believe that the gene that causes it is at least 25 million years old. In addition, an individual may acquire a delusional disorder known as clinical lycanthropy in which they truly believe they can transform into an animal. They have vivid hallucinations or false memories of the event and they may engage in animal-like behaviours such as growling, howling, walking on all fours and changing their diet. It’s a pretty unlikely combination but it’s entirely possible that a person could live quite happily into their adult life and then begin to grow hair all over their body, followed by episodes of disturbingly wolf-like behaviour.
A 1998 paper by neurologist Dr Juan Gómez-Alonso managed to link numerous aspects of the vampire legend to sufferers of rabies. Firstly, one sure fire way to catch the condition is to have a run in with an infected bat or wolf. Once the disease sets in, it begins to affect your brain in various ways, sometimes causing you to seek lots of sexual activity (much like the hypnotic vampires of 1970s cinema) or simply bite people who get in your way. Rabies can also make you hypersensitive to a number of stimuli including direct sunlight and strong odours like that of garlic, meaning you’re probably going to be sleeping during the day and avoiding escargots at all costs.
If vampires exist, they are definitely not human. Human organism doesn’t tolerate drinking blood due to high does of iron. Therefore, self-identified vampires risk haemochromatosis (iron overdose), which may lead to a number of diseases.
“One sure fire way to catch the condition is to have a run in with an infected bat or wolf”
The modern zombie is a lot more versatile than the image that was first popularised in 20th century film and literature. Nowadays a zombie might be the victim of an infection or chemical weapon but the shambling corpses of old school horror movies stem from the black magic of Haitian and West African folklore. A theory proposed in the 1980s by American botanist Wade Davis offered a frightening suggestion of how a person could indeed seemingly die and come back to life. A carefully measured amount of tetrodotoxin (pufferfish venom) can induce a deathlike state that could fool any skilled doctor. The heart rate and breathing slow down to an undetectable level and so the victim is pronounced dead and subsequently buried. The zombie’s master can then exhume the body in secret a few days later and administer a poison from flowers known as Datura or angel’s trumpets, which permanently damages brain function resulting in delirium and suggestibility. The victim is now a mindless, shambling slave.
In 2004, toxicologist Albert Donnay wrote of Mr and Mrs H who moved into their house in 1912 and soon began hearing footsteps, slamming of doors and pots and pans crashing in the kitchen. There were cold patches in the air and they felt as though they were being watched. Mrs H sometimes saw a woman in black in her mirror and once awoke paralysed with two eerie figures sitting at the foot of the bed. Even her young son woke up one night screaming “Don’t let that big fat man touch me”. Interestingly though, many of the family’s potted plants began to die, Mrs H complained of headaches and the children were “pale and listless”. A thorough inspection of the house revealed that their furnace was leaking the odourless gas, carbon monoxide, which binds with red blood cells much more readily than oxygen does. The subsequent oxygen deprivation leads to fatigue, headaches, delirium and auditory and visual hallucinations. Donnay believes that this is why ghost sightings were particularly frequent in the Victorian era, when the use of gas lamps was widespread.