New CDC program focuses on those already infected
Focus shifts to HIV treatment as form of prevention
From its onset, HIV was set apart from other diseases because prevention efforts were aimed at people who weren't infected, rather than those who were. Propelled in part by the likelihood that new drug regimens can make HIV-positive people less infectious, the Centers for Disease Control and Prevention is launching a program to provide comprehensive HIV prevention services to those already infected.
"Epidemiologically, we have always known that if you want to make a difference in an epidemic, you go with the people who are already infected and figure out how to keep them from continuing transmission. But for HIV, for all the historical reasons, that was not necessarily the strategy that worked in the beginning," says Helene Gayle, MD, MPH, director of the CDC's Center for HIV, STD, and TB Prevention. "Better treatment has shifted the treatment options, and also has shifted this whole area of focusing on HIV-positive persons for prevention."
Beginning with a $3.9 million effort to fund up to five long-term demonstration projects later this year, the agency is developing and assessing program service models for prevention in HIV-positive people that can be expanded and adapted across the country, says Gary West, a public health advisor in the CDC's Division of HIV Prevention. Once the demonstration projects help identify what a comprehensive prevention program should look like, the CDC could increase funding in this area by using money from existing cooperative agreements, he adds.
The initiative has four main goals:
· increasing the number and proportion of people who know their HIV serostatus as early after initial infection as possible;
· providing HIV primary prevention services to HIV-infected people;
· assisting HIV-infected people in accessing medical care, antiretroviral treatment, and other needed services;
· strengthening quality assurance and training and technology transfer systems for services provided to HIV-negative and HIV-positive people who are at high risk.
Scientific breakthroughs prompt new focus
With increasing evidence that lowering viral load translates into decreased HIV infectiousness, the nation's leading disease prevention agency has a legitimate role in focusing on HIV treatment, says Rob Janssen, MD, deputy director of the CDC's Division of HIV/AIDS Surveillance.
"What has been found generally is that triple therapy lowers viral load in blood plasma, and in addition, in many people, it reduces viral load in semen and vaginal secretions," he says. "The argument is that viral load is potentially a proxy for risk of transmission, and thus would strengthen the role for the CDC to be involved in treatment."
A number of recent studies have shown that viral load can be reduced to undetectable levels in semen as well as in plasma in some patients. But the effect is not consistent across the board, Janssen says. In a poster presentation at the Fourth Conference on Retroviruses and Related Opportunistic Infections in Chicago this year, 11 of 15 study participants had undetectable virus in semen, yet three of those 11 still had integrated viral DNA in semen cells.
Lowering risk, but not eliminating it
"You can get rid of HIV RNA in blood plasma and semen, but you can't seem to get rid of nonreplicating latent virus," he explains. "So that would say there is still a risk of transmission - you lower but don't eliminate it."
There are no data yet showing directly that potent antiretroviral therapy has led to decreased infectiousness. A suggested effect is implicit in preliminary data from an ongoing survey of gay men in San Francisco showing that the incidence of HIV in testing sites had remained flat just prior to the introduction of triple-combination therapy and has decreased since then. Blinded sexually transmitted disease specimens from San Francisco patients have been collected and surveyed from 1989, and results are available so far through 1994. If HIV incidence decreases in 1996 and 1997, this could show indirectly that the new treatments may result in lowered infectiousness, Janssen adds.
In addition to increasing HIV testing and helping people get into treatment, the CDC's role in the treatment arena also would center on compliance and resistance issues, Janssen notes. The use of directly observed treatment for tuberculosis patients may be a potential model for HIV treatment, he adds.
Janssen also notes that researchers at the University of California at San Francisco will soon publish a paper reporting on a case of sexual transmission of a multidrug-resistant strain of HIV. The patient, whose blood happened to be drawn on the day he transmitted the virus, had a viral load of 25,000 copies. It is the first documentation of a person's viral load being known on the day of transmission, he added.
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