Desperate heroin users in a few African cities have begun engaging in a practice that is so dangerous it is almost unthinkable: they deliberately inject themselves with another addict’s blood, researchers say, in an effort to share the high or stave off the pangs of withdrawal.

The practice, called flashblood or sometimes flushblood, is not common, but has been reported in Dar es Salaam, Tanzania, on the island of Zanzibar and in Mombasa, Kenya.

It puts users at the highest possible risk of contracting AIDS and hepatitis. While most AIDS transmission in Africa is by heterosexual sex, the use of heroin is growing in some cities, and experts are warning that flashblood — along with syringe-sharing and other dangerous habits — could fuel a new wave of AIDS infections.

“Injecting yourself with fresh blood is a crazy practice — it’s the most effective way of infecting yourself with H.I.V.,” said Dr. Nora D. Volkow, director of the National Institute on Drug Abuse, which supports the researchers who discovered the practice. “Even though the number who do it is a relatively small group, they are vectors for H.I.V. because they support themselves by sex work.”

Sheryl A. McCurdy, a professor of public health at the University of Texas in Houston, first described the practice five years ago in a brief letter to The British Medical Journal and recently published a study of it in the journal Addiction.

“I don’t really know how widespread it is,” said Dr. McCurdy who is contacting other researchers working with addicts to get them to survey their subjects about it. “There’s pretty circular movement in East Africa, so I wouldn’t be surprised if it’s in other cities.”

Increasing use of heroin in parts of Africa has the potential to magnify the AIDS epidemic.

In most East African countries like Tanzania and Kenya, only 3 to 8 percent of adults are infected with the AIDS virus, far fewer than in southern Africa, where the rates reach 15 to 25 percent.

But among those who inject heroin, the rates are far higher. In Tanzania, about 42 percent of addicts are infected. The rate is even higher — 64 percent — among female addicts, Dr. McCurdy said, and since most support themselves through prostitution, they are in two high-risk groups, and their customers are at risk of catching the disease.

Most of the addicts she has interviewed who practice flashblood, Dr. McCurdy said, are women. For them, sharing blood is more of an act of kindness than an attempt to get high: a woman who has made enough money to buy a sachet of heroin will share blood to help a friend avoid withdrawal. The friend is often a fellow sex worker who has become too old or sick to find customers.

By contrast, on Zanzibar, it is mostly among men, according to a 2006 study in The African Journal of Drug and Alcohol Studies, which found that about 9 percent of the 200 drug-injectors interviewed practiced it.

There have also been reports in East African newspapers of addicts selling their blood, but those have not been confirmed by medical researchers.

And, there have been scattered reports of flashblood-type practices in other countries with large numbers of heroin addicts, including Pakistan, but they also have not been confirmed by researchers.

Whether or not someone can actually a get drug rush from such a relatively tiny amount of blood has never been tested, Dr. McCurdy said. Humans have about five quarts of blood and the flashblood-user injects less than a teaspoon.

“They say they do,” she said. “They pass out as if they just got a high. But I’ve talked to doctors who say that could be entirely the placebo effect.”

One possibility, she said, is that traces of the drug are still in the syringe. After piercing a vein, an addict will typically draw some blood into the syringe, push it back out and repeat that three or four times to make sure all the heroin has been flushed into their blood. Those offering flashblood will usually hand over the syringe after only one in-out cycle.

The heroin sold in East Africa, she added, is often quite strong because it has come from relatively pure shipments on their way to Europe from Afghanistan or Asia.

Until recently, heroin use was uncommon on the continent because most Africans are too poor for traffickers to bother with. But in the last decade, smugglers have begun using port cities like Dar es Salaam and Mombasa and airport cities like Nairobi and Johannesburg as way stations on their routes: law-enforcement officials can often be bribed, and couriers from countries with no history of drug smuggling may escape searches by European border officers. The couriers may be paid in drugs, which they resell.

With more local users, more heroin is being sold in Africa. In the last decade, law-enforcement and drug treatment agencies said, heroin use has increased, especially in Kenya and Tanzania, South Africa and Nigeria. Brown heroin that must be heated and inhaled — “chasing the dragon” — has given way to water-soluble white heroin that can be injected. Prices have fallen by as much as 90 percent.

While a teaspoon of blood is more than enough to transfer diseases like AIDS, said Dr. James AuBuchon, president-elect of the American Association of Blood Banks, it would not be enough to cause a life-threatening immune reaction, as can ensue when a patient gets a transfusion from someone of the wrong blood type. Instead, “you’d likely get only brief symptoms,” he said.

Dr. AuBuchon, who practices in Seattle, said he had never heard of flashblood, but added that he was horrified by the idea.

“What,” he asked, “are they thinking?”

Source: New York Times