At his most hungry, Belfazaar said he has ingested six ounces of blood, but warned normal humans, -- who, he said, are known as "mundanes" in vampire lingo -- that drinking blood can you sick "if you are not a true sanguine."
This strange "feeding" is what Belfazaar and others say they need to stay healthy, but it can also be an erotic experience for those who participate.
"It's a rush of energy. There's a bond between the two individuals," said Bo.
"Even though the vampires are taking from someone there is an energy that we give off," said Belfazaar. "For some people, they describe it as calming, other people describe it as sensually arousing."
Jade, who reads tarot cards in the French Quarter, is also an elder in the New Orleans vampire community, and told 20/20 that she needs to feed on sex and blood -- the more the better.
"I can do it once a week and stay balanced. I can do it twice a week and stay happy. I can do it daily and just be really happy."
Not all so-called vampires identify themselves as sanguine, or blood drinking vampires; however, most interviewed by "20/20" admit that they have at one time or another tried drinking blood.
Doctors say that feeding on blood has no medical value.
"To ingest the blood, biologically speaking, it has no value whatsoever in making any medical difference," said Dr. Jeffery Hobden, an infectious disease expert at the LSU Health Sciences Center. "The placebo effect can be very powerful."
It can also be dangerous.
"Not only is the person who's ingesting the blood at risk, but the person who is donating the blood who was cut is also at risk from infection," said Hobden.
What's more, if the blood is tainted with HIV, hepatitis or other viruses, they can be introduced into the bloodstream through any cut in the mouth or gums. There could also be unidentified dangerous blood-borne viruses that could be sources of disease.
Belfazaar said he and his donors are tested regularly. He said he also believes he is somehow immune to infections.
"I've been doing this since I was 13, so that's 31 years of never being bothered by any of the other infections," he said. "So if there's something that bothers a normal -- what we call a mundane -- human, for some reason they don't bother me."
In her fourteen years of drinking blood, Jade said she has fed thousands of times, using her judgment to screen potential donors.
"I'm very picky about my donors. Some people go for medical testing. I find that too expensive. I just use my own perceptions and I'm never wrong."
Dr. Hobden says that kind of thinking could be deadly. "I'm sure that some of these folks, we'll be seeing them in the hospitals with failing livers from chronic hepatitis or liver cancer," he said. "The danger is very real."