Nov. 25 (Bloomberg) -- Testing everyone for the AIDS virus in hard-hit African countries and treating all infections immediately may eliminate most of the disease’s spread, according to a computer simulation of the epidemic.

About 1.9 million people were infected with the AIDS virus, called HIV, in southern African countries in 2007, according to UNAIDS, the New York-based agency that coordinates the United Nations’ response to the epidemic. Universal testing and treatment might cut the spread of the lethal virus in southern Africa by 95 percent in 10 years, said researchers led by Kevin De Cock, director of HIV/AIDS for the World Health Organization in Geneva, in the Lancet journal.

The study hinges on emerging research suggesting that effective antiviral treatment can keep levels of the virus so low in people that the possibility it will spread is almost nil. The findings are theoretical, and WHO is not changing its recommendations regarding HIV testing or drugs, De Cock said. Still, the research suggests that giving patients drugs as soon as they’re diagnosed could benefit millions of people.

“The concept of antiretroviral treatment for HIV prevention is a very important, urgent thing to examine,” he said in a statement. “We aim to stimulate discussion about what is probably the most important question in HIV prevention: when to start therapy?”

HIV infected 2.7 million people worldwide in 2007, UNAIDS said. Since Merck & Co.’s AIDS vaccine failed last year, researchers have said that no experimental candidate is likely to gain approval for at least 10 years.

Stopping HIV’s Spread

The Lancet study looked at aggressive treatment of infected people as another possible way of preventing HIV’s spread. Combinations of drugs, such as Bristol-Myers Squibb Co.’s Sustiva along with Gilead Sciences Inc.’s Truvada, can keep viral levels so low that HIV is undetectable by conventional means. Studies have suggested that keeping the virus in check this way may lower the chances an infected person will spread the virus to others.

Scientists are testing whether they can prevent infections with daily doses of Gilead’s Viread or Truvada in uninfected people. Regular condom use, male circumcision and abstinence from sex can reduce the risk of infection.

Swiss health officials said in January that people infected with undetectable levels of HIV who don’t have other sexually transmitted diseases should be considered unlikely to transmit the virus to others. Universal treatment in Africa might yield dramatic results, said Pietro Vernazza, head of the Swiss Federal Commission for HIV/AIDS.

Call for Wide Treatment

“If people want to be treated, and we have the resources, we should just start to do it,” he said today in a telephone interview. “We could have a huge impact on transmission.”

Testing everyone in a country annually would also be a huge challenge, De Cock said. Only about one in five people in African countries currently knows their HIV infection status, and the right to refuse testing and treatment also must be considered, he said.

The study projected infections in a southern African country of about 50 million people. The annual cost of testing and treatment at the outset would be about $1.7 billion, but would probably begin falling in about 20 years, the researchers said. Wider treatment would probably cut costs for other diseases often linked to HIV, such as tuberculosis and malaria, said Reuben Granich, a WHO medical officer who helped write the study.

HIV attacks the immune system’s directors, called CD4 cells. Doctors usually begin treating HIV when low CD4 cell levels leave patients vulnerable to other diseases. A study released last month at an infectious disease meeting in Washington suggested the accepted level, 200 cells per cubic millimeter of blood, was too low and that treating people earlier, when the level drops to 350 or below, might save lives.

Treatment Can be Lifelong

Once people begin receiving HIV drugs, they generally keep taking them for the rest of their lives. There is increasing evidence that early therapy provides benefits and may cut the spread of HIV, said Myron Cohen, a University of North Carolina at Chapel Hill AIDS researcher.

“It seems clear that we need longer studies to determine the durability of personal and public health benefits of antiretroviral therapy,” he said Nov. 22 in a telephone interview.

Only about 3 million people in Africa are getting AIDS medications now, while 8 million to 10 million meet the current criteria for treatment, said Michel Kazatchkine, executive director of the Global Fund to Fight AIDS, Tuberculosis and Malaria in Geneva. Overall, about 22 million people in southern African countries are infected. Programs are being expanded as quickly as possible and may reach almost 4 million people in Africa by year’s end, he said.

“The demand that we are receiving from countries is increasing enormously and growing faster than we anticipated,” he said Nov. 21 in a telephone interview.

To contact the reporter on this story: John Lauerman in Boston at jlauerman@bloomberg.net.

Last Updated: November 25, 2008 19:01 EST