March 29, 2000 (Atlanta) -- A new study finds that the amount of HIV in an infected person is the main predictor of who will most likely infect their sexual partner: High HIV levels in the blood make sexual transmission more likely. Although there is no proof that AIDS drugs that help reduce the amount of virus in the body make people with HIV less likely to infect their sex partners, one expert is concerned that this study, published in the March 30 issue of The New England Journal of Medicine, will lead to an increase in unsafe sex among HIV-infected people.
It would be a disaster for people now taking anti-HIV drugs to begin practicing unsafe sex, warns Myron S. Cohen, MD, director of the University of North Carolina, Chapel Hill, center for infectious diseases. Even if the drugs do reduce infectivity, he tells WebMD, they will never by themselves wholly prevent transmission. As chairman of the antiretroviral therapy working group of the HIV Prevention Treatment Network, he is organizing clinical trials to test the idea. Cohen predicts that the study marks the beginning of a new era in AIDS prevention.
"Most of our prevention effort has focused on the behaviors of people at risk -- but what are our obligations for people who are already infected?" he asks. "We want to deal with them with respect, and find ways to help them avoid passing HIV to the next person. This study is helpful in refocusing our attention on this group."
"There is an urgent need to do an antiviral drug trial to see if when we reduce viral load, we reduce transmission," Thomas C. Quinn, MD, lead author of the study, tells WebMD. "Antiretroviral drugs need to be made less expensive and available in the developing world. But perhaps more importantly, if in the process of developing vaccines for HIV we come up with a vaccine that could lower viral load that would be cost effective and applicable throughout the world -- that would be the magic bullet to shoot down this disease throughout the world. I urge researchers to work toward this goal."
The study, sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), enrolled more than 400 heterosexual couples living in rural Uganda. In each couple, one partner was HIV infected and the other was not. Even though the researchers gave away condoms and provided safe-sex counseling, 90 of the uninfected partners came down with HIV infection over the course of the study.
Like most of Africa, people in Uganda cannot afford AIDS drugs and their government cannot afford to provide them. The amount of virus in the body, known as the viral load of the HIV-infected person, was the most important factor determining whether HIV was transmitted to their sex partner. The higher the HIV level, the higher the risk of transmission. The people with the lowest HIV levels, less than 1,500 copies of the virus per milliliter of blood, did not transmit the virus at all.
Another major study finding is that circumcision seems to have protected men from getting HIV. None of the study's 50 circumcised men got HIV from their infected partner, while nearly 30% of the uncircumcised men became infected with the AIDS virus. This may help explain why in the U.S. -- where Cohen says some 70% of men are circumcised -- HIV is more efficiently transmitted from men to women than from women to men. In Africa, where most men are not circumcised, rates of male-to-female and female-to-male HIV transmission are about the same.
Carlos del Rio, director of Emory University's international AIDS training and research program, reviewed the study for WebMD and praised the work of Quinn and colleagues. "I think this study is very, very important," he tells WebMD. "What's most relevant is the fact that circumcision appeared to be protective. This would be evidence that would sway me to urge circumcision."
Although the study was approved by all of the institutions involved -- including those of the U.S. National Institutes of Health, Johns Hopkins and Columbia universities, and Uganda's AIDS Research Subcommittee -- it has drawn considerable criticism from medical experts who say it was unethical. These critics have two major objections. First, they say that the U.S. researchers should have given all of the study participants antibiotics and anti-HIV drugs when they were needed. Second, they are seriously disturbed that the researchers did not tell people that their sex partners carried the AIDS virus -- even though Ugandan research rules specifically forbid telling anyone whether a person is infected with HIV.
Cohen and del Rio defend both Quinn and the study. "I think they did remarkable job under difficult conditions," Cohen says.
Del Rio is even more emphatic. "Is there a double standard for ethics? I think this study was ethical -- it needed to be done, it had important implications for the country in which it was done," he says. "We should not try to impose an ethical standard on another country. Is our standard of care the standard we need to have everybody abide by? ... This is an issue of ethical imperialism: Do we need to tell people in other countries how to act? Partner notification has not been a standard of care in this country -- we don't go and track infected partners. Why should we ask another country to do it?"