A recent article in the British Medical Journal suggests 40 percent or more of the HIV/AIDS cases in sub-Saharan Africa are due to unsterilized hypodermic needles. The authors say the needles are often reused at hospitals or clinics or by street dentists.

The authors say there?s growing evidence contradicting the belief that heterosexual sex is the cause of nearly all HIV infections. They say evidence has been ignored since the 1980?s that indicates the use of unsterilized hypodermic needles is a major factor in transmission of the AIDS virus.

John Potterat has worked in the public health service for 35 years and is co-author of the article. He says, "There isn?t enough sex going on out there to explain what?s going on. I think if you really look at the data very closely, the fury of the epidemic ? particularly in developing countries ? is such that sex cannot possible account for it. So, we began to think in terms of what else could it be?"

He says risk factors such as sexually transmitted diseases and lack of circumcision do not explain the extent of Africa?s AIDS epidemic.

Co-author David Gisselquist, an independent consultant, says the evidence supports their theory. "If we look at the evidence for sexual transmission and sexual behaviors in countries with high prevalence," he says, "there?s just too much HIV to be explained by what we know about heterosexual transmission. The second line of evidence is that if we look for evidence of transmission through health care, we find just a tremendous amount of evidence for substantial levels of HIV transmission through injections and other kinds of health care."

Of the 40-million people estimated to be infected with HIV, the virus that causes AIDS, 28-million are in sub-Saharan Africa. The U-N AIDS program says HIV/AIDS is now the leading cause of death in sub-Saharan Africa. Many of the programs to raise awareness about the disease concentrate on safe sex and the use of condoms. But Mr. Potterat says more awareness is needed about safe medical practices, including the sterilization of needles. He says contaminated needles can pose a greater risk than unprotected sex. "A needle is far more effective as far as efficiency of transmission than penises are," he says. "Transmission rate is far easier that way. If I were an HIV I would rather be transmitted by a needle than by a penis and have a greater chance of survival."

David Gisselquist says making sure hypodermics are sterile could deal a major blow to the spread of AIDS. "It just needs a lot more attention and a lot more public discussion. And this hasn?t been forthcoming. There?s been too little emphasis on these risks. With attention it could be solved very quickly and could have a substantial impact on the HIV epidemic."

The authors say used needles must be properly disposed of to ensure they are not stolen from the trash and used by street dentists or drug addicts.

They add their findings support efforts by the Safe Injection Global Network, which was formed by public and private health groups in 1999. The Network is based at the World Health Organization headquarters in Geneva.