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Today is the 13^th annual , and it has been 30 years since that first ominous report of among previously healthy young men in Los Angeles.

Health officials estimate that about 60 million people worldwide have been infected with the and that about half of them have died. In the United States, just over a million people have been diagnosed with AIDS since the epidemic began in 1981 and almost 600,000 have died.

HIV infections, which suppress the immune system so opportunistic infections can take hold, are responsible for the resurgence of , especially in Africa.

And there鈥檚 still no聽,聽despite all the research into HIV and over two dozen ongoing trials of candidate agents.

These aren鈥檛 the kind of facts and figures that engender a lot of hope or give cause for celebration.

Reasons for optimism

Yet there鈥檚 actually more reason now to be optimistic鈥攃autiously optimistic, ever so cautiously, and with caveats鈥攁bout the course of the HIV/AIDS epidemic than there has been in years.

Here鈥檚 why:

• The epidemic seems to have peaked (for now). Many of the important indices of the epidemic鈥攏ew HIV infections, new AIDS diagnoses, AIDS-related deaths鈥攈ave peaked and trend lines have a downward slope. , the special international agency created to deal with the epidemic, estimates there were 2.7 million new HIV infections worldwide in 2010, which is 21% fewer than the peak of 3.2 million in 1997. AIDS-related deaths fell to 1.8 million last year, according to the agency, down from a peak of 2.2 million during the mid-2000s. In the United States, the number of newly diagnosed cases of AIDS peaked in 1993, and the number of AIDS-related deaths has been decreasing since 1995.
• Drug therapy has turned HIV/AIDS into a manageable chronic disease. The antiretroviral (ARV) drugs that were first introduced in 1996 have changed HIV/AIDS from being a veritable death sentence into a chronic infection that can be hemmed in and managed for decades. Danish researchers have calculated that HIV-infected men in developed countries with access to ARV drugs and health care now have a life expectancy of about 75 years, provided they start treatment when their immune systems are relatively intact. That鈥檚 about seven fewer years of life expectancy than among those who aren鈥檛 infected, so there鈥檚 still a morbidity and mortality price to be paid. But it鈥檚 a lot less than it was before today鈥檚 sophisticated ARV drug regimens became available.
• Drug therapy prevents transmission of the virus. By reducing the amount of virus in an HIV-infected person鈥檚 body (鈥渓owering the viral load鈥�), ARV drugs also reduce transmission of the virus. 鈥淭reatment is 辫谤别惫别苍迟颈辞苍,鈥� , director of the federal Centers for Disease Control and Prevention (CDC), said emphatically during a press conference this week. For anyone familiar with the old treatment vs. prevention dichotomy in HIV/AIDS, it was stunning to hear them equated鈥攁nd by the director of the CDC, no less. But it makes sense. Early on, studies showed that treating HIV-infected mothers with ARV drugs dramatically reduced transmission of the virus to their newborn children. Now studies are showing that the drugs can prevent adult-to-adult transmission. In May of this year, results of a major international study of 鈥渟erodiscordant鈥� couples, nearly all of whom were heterosexual, were made public. The , as it is called, showed that if a person who is HIV positive starts taking antiretroviral drugs when his or her immune system is still strong, it reduces the chances of that person transmitting the virus to an uninfected partner by a stunning 96%. Another approach that uses drug therapy for prevention has been dubbed (PrEP): people take ARV medications on a preventive basis before they are infected so if they are exposed to HIV, the chances of becoming infected with the virus are reduced. CDC-sponsored studies have shown that PrEP works to substantially lower infection rates among gay and bisexual men in the United States and among heterosexual men and women in Africa.
• HIV cures are under investigation. ARV drugs corral HIV, but even if virus levels get very low, some HIV continues to hide out in the body. An HIV cure would get rid of the virus altogether鈥攐r, more plausibly, drive it down to such low, weakened levels that the immune system could control it on its own. Hope that a cure is feasible has been kindled by the case of , a leukemia patient whose HIV infection seems to have been cured (he stopped taking ARV drugs and tests can鈥檛 find the virus in his body) by the bone marrow transplants he received from a donor with a genetic mutation. This mutation is known to protect people from HIV infection by altering a protein on immune cells so they can resist the virus. Bone marrow transplants aren鈥檛 the answer, but researchers are investigating whether gene therapy might be used to modify the immune cells of HIV-infected individuals so they gain the resistance that some people have naturally. Other curative strategies under investigation involve early, aggressive treatment of HIV with ARV drugs in combination with other agents, with the goal of flushing the virus from its hiding spots in the body.

Mission not accomplished

Optimism is one thing. Foolish optimism is another.

The AIDS epidemic is far from over, and the downward slope of those trend lines could plateau or head up if prevention and treatment efforts slack off. The overalI trends don鈥檛 apply to everybody. In this country, new HIV infections are still increasing among young black men, both gay and bisexual, and the CDC launched the campaign this week in response.

And now the flip sides

Moreover, every bit of good news about HIV/AIDS has a problem- and question-filled flip side.

• If drug therapy has turned HIV/AIDS into a chronic condition, then what kind of side effects are HIV-infected people going to experience in their fourth, fifth, or even sixth decades of treatment?
• If treatment is the new prevention, will people have access to it? The price of ARV drugs has dropped, and the number of people in sub-Saharan Africa who are taking them has climbed in recent years. Still, only about half of the approximately 15 million people worldwide who might benefit from ARV drugs (for both treatment and preventive purposes) are receiving them. The CDC estimates that only 336,000 (28%) of the 1.2 million Americans who are HIV-positive are getting the kind of care that keeps viral loads low.
• Even if scientists were to find ways to cure people of HIV infections, will the cures be practical and affordable?

The list goes on.