HAART emerging as prevention tool

Dr Michael Rekart, Director of Sexually Transmitted Disease and HIV/AIDS Control at the British Columbia Centre for Disease Control, says he is more excited now than ever about developments in the prevention and understanding of the transmission of the human immunodeficiency virus (HIV).

“What’s most exciting,” he says, “is that if we move forward on these fronts, I think we can actually eliminate this virus; get it down to a level where it isn’t a huge issue anymore. The potential is there. The science is clear.

“People are starting to recognize that we need to do, and fund, new things if we’re going to make any progress. It’ll take some forward thinking, risk taking, and money, but I think we can do it.”

Rekart sees the new concept of using highly active anti-retroviral therapy (HAART) to prevent the spread of HIV as one of the most promising new initiatives.

For more than a decade, the HAART drug regimen has been the most powerful weapon in the medical arsenal for extending the lives of those living with HIV. But only recently have researchers come to realize that not only can the therapy save the lives of infected patients, it can also inhibit the transmission of the virus to others. It’s no longer just about treatment; it’s also about prevention.

“Almost every time you treat somebody you’re going to reduce their viral load,” says Rekart. “When you reduce the viral load you reduce the infection risk. So if you treated everybody that has HIV, you would certainly reduce the average viral load in the community which would have a prevention dividend.”

The idea was developed and presented by Dr Julio Montaner, Director of the BC Centre for Excellence in HIV/AIDS, at last August’s International AIDS Conference in Toronto.

“The most important development [in HIV treatment] has been our new understanding of the added preventive value of HAART,” Montaner says. “That refers to the fact that people [whose viral loads] are undetectable either naturally, or more frequently as a result of HAART, are less likely to transmit HIV.”

And, Montaner adds, HARRT is even more effective than it was just a few years ago.

“Tolerability of the regimens [are] dramatically better than in the late ’90s,” he explains. “They do require monitoring and some attention, but for the most part [they] are very reliable, very sturdy, and work very, very well. People who are treated with HAART today starting with CD4 counts of over 200 add decades of healthy living to their lives. There are very few conditions in medicine where the clinical benefit [is] as striking as has been now shown for HAART.

“If we were to treat everybody infected with HIV, one could conceive a scenario where HIV could slowly come under control,” Montaner continues. “New infections would decrease steadily, and our generation could leave behind an HIV-free world.

“It’s hypothetical at the moment,” he points out quickly. “It’s purely based on mathematical modelling and the assumption that HIV treatment works, is safe, well-tolerated, and people can do it without problems. That’s not that far in the future really.”

Even so, he is quick to emphasize that the success of this approach will depend on a continued commitment to other prevention strategies.

“We don’t believe, not for a minute, that the use of HAART can be an excuse to relax safer sex practices,” warns Montaner. “At the end of the day if you try hard enough, eventually you’re going to be able to transmit [HIV] despite the fact you have HAART on board.”

Rekart says, for example, that controlling other sexually transmitted infections will also be necessary to defeat HIV.

“Probably the best defence we have against most infections, including HIV, is our skin, which is the equivalent to the mucous membrane in the vagina, [and] the mouth,” he explains. “When you have an STD, even if it’s a mild [one] like candida, and you look at the mucous membrane under a microscope, you’ll see that it’s torn and jagged. The virus doesn’t have to fight through [it] to get into the system; it has an easy entry.

“When we have an STD,” he continues, “our body’s reaction is to send cells to the point of the infection to fight [it]. Unfortunately, one of the cells that fights STDs is the primary target for HIV, the CD4 cell. When a person has gonhorrea, the body sends all kinds of CD4 cells to the point of the infection. If HIV comes around, there are easy targets for [it] to infect. That cofactor relationship has been shown for almost every STD.”

Rekart acknowledges that health professionals have talked for many years about STDs as cofactors in HIV transmission, but worries that the community doesn’t fully understand their importance.

“In some studies,” he continues for example, “40 percent of all new HIV infections are associated with previous herpes infections. Herpes is everywhere in BC. At least 29 percent [of] the adult population has had herpes 2, what we used to call genital herpes.”

And of course routine testing is still critical, says Rekart, citing “small but significant rises in HIV infections since 2000” in gay men in the Lower Mainland.

“If [sexually active] means you have new partners frequently, and unprotected sex, or sometimes unprotected sex, then I don’t think [testing] monthly would be too often,” he says. “If you are talking more in the moderate range of sequential partners–maybe two or three a year, and mostly protected sex–then probably at the point you have a new partner might be a good time to do it, or maybe every three or four months.”