Nov. 27, 2009 — -- They roam our streets and tend to the sick. People who describe themselves as real-life vampires have found ways to live quietly among us.
"I'm not going to worry and waste sleep at night over who might think I'm a little kooky, because I think I'm a vampire," said Kiera, a registered nurse who works in a hospital in Atlanta. She did not want to be identified by her real name.
Throughout the country and all over the world, a hidden subculture of people believe they are real vampires. They claim to have an "energy leak," which makes them feel sick and lethargic. To offset this energy imbalance, they say they need to feed on other people's energy or blood.
"I try to be very ethical about what I do. I feed predominantly from crowds, so as not to cause harm," said Kiera, a founding member of the Atlanta Vampire Alliance.
Kiera considers herself a "psychic" vampire. Other vampires known as "sanguinarians" or "blood-drinkers" claim to feed on the blood of consenting donors. Kiera said she has tried this before.
"I have bitten people and had a very small taste of it, but I don't seek out blood donors to collect blood from and ... drink," she said.
Doctors caution that ingesting or donating blood without the proper medical equipment is very dangerous, as it puts participants at risk for infectious diseases like HIV and hepatitis.
Today's self-described vampires do not claim to be immortal or have superpowers. And they say they don't prey on strangers. They have willing donors, who often are friends or lovers.
CLICK HERE to meet "real-life vampires" featured in the "20/20" piece.