In rural Tlaxcala, Mexico the vampire witches known as tlahuelpuchi are much feared. At least a hundred legends about tlahuelpuchi exist. The tlahuelpuchi was a person believed to possess magical powers, including the power to transform themselves into one of several animals and in that form attack and suck the blood of humans. They can be of either gender, but usually are females, who are considered to be the more bloodthirsty and evil of the two. Elements found in tlahuelpuchi can be traced to ancient Aztec goddesses. Their archetype was further modified to include influences from the witches of Spain when the country was converted to Christianity.
Tlahuelpuchis are born into their fate; they cannot transmit or teach their powers to others. They are independent agents of evil, but will do the bidding of higher evil forces, such as the devil. When a tlahuelpuchi is born, it cannot be distinguished from an ordinary infant. Differences do not emerge until puberty, at which point their supernatural powers such as shape-shifting suddenly manifest. For females, this often occurs with the onset of the menses. When the powers manifest, the tlahuelpuchis of both sexes begin to have a life-long, uncontrollable urge to drink human blood. They will drink the blood of any human but have a marked preference for that of infants between the ages of 3 and 6 months, but no younger. They prowl about at night, particularly between the hours of midnight and four a.m., but will operate during the day if their blood craving is extreme. Tlahuelpuchis are not out every night, but only when they experience their uncontrollable blood cravings, which ranges from one to four times a month. They are more active during rainy and cold weather.
Finding a tlahuelpuchis to be among them causes families a great deal of unhappiness and shame. The will go to great lengths to cover it up to avoid being ostracized by the community. It's said tlahuelpuchis cannot attack members of their own families, unless they reveal their secret. Although tlahuelpuchis cannot transmit their powers to others of their own volition, if they are killed, their powers go into the killer. This places the family in the position of reluctant accomplices.
The most common animal into which the witches transformed themselves was a turkey, but animals as varied as fleas, cats, dogs, and buzzards were reported. When shape-shifted, they are limited to the abilities of that particular creature, and cannot make it perform in magical ways -- with one exception: they can make turkeys fly. When in animal form, they give off a luminescence or phosphorescence that is a tell-tale sign of their identity. They steal into a home as a mist, sometimes luminous, that seeps under doors and windowsills, or through keyholes, or they crawl in as an insect. Once inside, they shape-shift into a turkey or buzzard, and hypnotize the occupants into a deep sleep so that they can carry out their attacks.
The tlahuelpuchi also have hypnotic power over individuals and could cause them to kill themselves, primarily by having them walk to a high place and jump to their death. They might kill or injure domestic and farm animals and could ruin crops. Thus many types of misfortune were attributed to the work of witches. For obvious reasons tlahuelpuchi lived incognito in the communities.
Belief in the tlahuelpuchi is widespead in Mexico and continues to this day in rural areas. Cases of tlahuelpuchi attacks have been recorded in modern times, some resulting in the trial and execution of the alleged vampire. As recently as 1954 the state of Tlaxcala passed a law requiring that infants reportedly killed by witchcraft had to referred to medical authorities. While in almost every extended Tlaxacalan family there will be reports of multiple bloodsuckings over the course of generations, the accusations of bloodsucking witchcraft that result in trial and execution historically have not been common, and have declined considerably since the late 19th and early 20th centuries. The last known execution of a tlahuelpuchi, a woman, occurred in 1973
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http://www.lesvampires.org/mirrorsportal/tlah.html