A cure for AIDS remains a distant prospect but a host of drug treatments and other advances have fueled fresh hope that new human immunodeficiency virus infections may some day be halted for good.
Strategies for ending the 30-year AIDS epidemic through advances in treatment, testing and prevention are high on the agenda of a major meeting of experts in HIV/AIDS when it returns to the United States next week after two decades.
"What we know is absolutely possible is that we can end the pandemic even without having a cure," said Anthony Fauci, a leading AIDS expert and director of the National Institute of Allergy and Infectious Diseases.
Held every two years, the International AIDS Conference has convened elsewhere around the world but not in the US since 1990, due to a travel ban on HIV-positive individuals.
The ban was overturned by US lawmakers under president George W. Bush in 2008 and signed into law by President Barack Obama in 2009.
The conference's return to the United States was expected to draw a star-studded crowd of 25,000 -- more than the usual 20,000 -- including celebrities, politicians, AIDS activists and scientists, organizers said.
Among the key speakers are singer Elton John, former US president Bill Clinton and philanthropist Bill Gates. Democracy icon Aung San Suu Kyi of Myanmar will address the conference by videolink.
A pre-conference bash staged by amfaR, the American Foundation for AIDS Research, on July 21 will feature actors Sean Penn, Sharon Stone and prominent CNN newsman Anderson Cooper, who recently came out publicly as gay.
A series of pre-conference talks and announcements will also set the stage for the six-day meeting in the US capital, themed "Turning the Tide Together," which formally starts on July 22.
On July 19, French Nobel laureate Francoise Barre-Sinoussi, the co-discoverer of HIV, will announce the release of a new global strategy toward a cure that aims to tackle the reservoirs where HIV holes up after it has been attacked by antiretroviral drugs.
"The strategy aims to build a global consensus on the state of research in the HIV reservoirs field and define a roadmap of scientific priorities that must be addressed by future research to tackle HIV persistence in patients on antiretroviral therapy," said a statement by the International AIDS Society.
Another key point is the use of antiretroviral drugs as both treatment and prevention, building on a series of studies that have shown promise in giving the drugs to infected people early and even prescribing them to uninfected partners at risk.
"We see this as probably being a central conversation at the conference -- the appropriate initiation for treatment and also how to best take advantage of antiretrovirals for prevention more broadly speaking," said the World Health Organization's HIV/AIDS chief Gottfried Hirnschall.
The WHO will be releasing new guidelines for using HIV drugs as prevention, a strategy known as pre-exposure prophylaxis that has shown some success but also some failures in recent studies.
Funding gaps remain a big concern among experts, with the United Nations funding target set for $22-24 billion globally and the available cash for responding to HIV at just $15 billion in 2010.
Experts will also appeal for a jumpstart to current prevention strategies, which Fauci says have to accelerate in order to end the pandemic that has killed some 25 million people to date.
"If the current slow rate of decline in infections globally -- on average just 1.5 percent per year over the past decade -- were to continue indefinitely, controlling HIV/AIDS would remain a distant goal," he wrote in Health Affairs magazine in July.
Fauci and co-author Gregory Folkers, his chief of staff, called for optimal use of the prevention "toolkit" that researchers now have at hand.
In addition to antiretrovirals for treatment and prevention, those tools include microbicides that show some effectiveness against HIV when applied to the vagina or rectum, showing up to 54 percent fewer infections in women who used them at least 80 percent of the time.
Voluntary male circumcision has shown some success in Africa toward reducing HIV infection rates by 50 to 60 percent in heterosexuals compared to uncircumcised males.
And researchers are gleaning more clues from a 2009 vaccine trial in Thailand that showed a modest 31 percent reduction in HIV infection, and hope to improve on those results in future trials.
Drugs 'arsenal' could help end AIDS: WHO
Thirty years into the AIDS epidemic, a cure remains elusive but a growing arsenal of drugs could someday help end new infections, the World Health Organization's HIV/AIDS chief says.
The key is figuring out how to best manage the latest advances, Gottfried Hirnschall said in an interview with AFP during a visit to Washington this week ahead of the International AIDS Conference that begins here July 22.
Antiretroviral drugs may reduce the risk of infected people passing on the virus, and may prevent healthy people from becoming infected through sex with HIV-positive partners, but the new possibilities have also stirred controversy.
Still, these medications saved about 700,000 lives worldwide in 2010 alone, which experts have described as an extraordinary accomplishment.
Research breakthroughs and progress in some countries "demonstrate that it is possible to really advance significantly in scaling up the response and even start to think about eliminating new infections," Hirnschall said.
The world now has 26 antiretroviral (ARV) drugs on the market and more in the pipeline for treating people with human immunodeficiency virus, which has infected 60 million people and killed 25 million since the epidemic first emerged.
"We have a fairly large arsenal of drugs available," Hirnschall said, noting that the drugs are better now than they used to be -- less toxic, more robust, less likely to trigger resistance and more tolerable -- but are still not perfect.
Side effects remain a concern, and officials are carefully monitoring the emergence of resistance, with the WHO set to release its first global report on drug resistance in low and middle income countries on July 17.
Recent studies have shown the potential benefits of starting treatment early, before the viral load gets too high, as a way to protect an infected person's health and lower the risk of passing the disease to a partner.
Research on using ARVs as a way to prevent HIV in healthy people -- also known as pre-exposure prophylaxis or PrEP -- has shown conflicting results, with some promise seen in studies on heterosexual couples and gay men who took the pills faithfully.
However, one major study of African women failed to show any protection from ARVs compared to a placebo and had to be stopped early.
"We see this as probably being a central conversation at the conference -- the appropriate initiation for treatment and also how to best take advantage of antiretrovirals for prevention more broadly speaking," Hirnschall said.
A US advisory panel has urged the Food and Drug Administration to approve the first-ever HIV prevention pill, Truvada by Gilead Sciences, for use in some high-risk populations. A decision is expected by mid-September.
Truvada is already on the market as a treatment for people with HIV.
But some health care workers fear that the availability of a pill that could reduce the risk of getting HIV may encourage people to stop using condoms and spark a rise in risky sex behaviors.
Others are concerned about the ethics of providing HIV drugs to healthy people, when vast numbers of infected people across the world still do not have access to life-saving treatments.
And some high-risk groups remain difficult to reach, such as sex workers and injecting drug users who are often shut out from treatment due to restrictive laws.
"In many countries where they (drug users) constitute the major risk group, they have lower access to treatment," Hirnschall said.
"We also know that in many places, men who have sex with men cannot access services in general, or sex workers by the same token because they are stigmatized, they are criminalized in many countries and it is not easy for them to come forward to be tested and then to access services."
The WHO is also working up a set of guidelines for administering antiretrovirals as prevention to healthy people that should be available in time for the conference.
PrEP "is a promising approach. We believe it is one that is probably becoming a niche intervention for certain individuals where other preventions may not be accessible or may be difficult to implement," Hirnschall said.
"There are very few magic pills. But it might be one additional intervention that we could add to the arsenal of interventions that we have."
Hirnschall said he was "very optimistic about the conference," the first to be held in the United States since 1990 and made possible due to the lifting of travel restrictions on HIV positive people by Washington a few years ago.
"We will hear from countries what is happening on the ground," Hirnschall said.
"The challenge is not just to set brave policies but really to have the capacity and resources that it takes to implement those."
Facts about HIV/AIDS worldwide
Here are some key facts and figures on HIV/AIDS, ahead of the International AIDS Conference set to take place in Washington on July 22-27.
About 34 million people were living with HIV at the end of 2010, according to the World Health Organization.
An estimated 2.7 million people worldwide were newly infected with HIV in 2010.
TRENDS IN NEW INFECTIONS
Since 2001, annual HIV incidence has fallen in 33 countries, 22 of them in sub-Saharan Africa.
HIV is on the rise in Eastern Europe, Central Asia, the Middle East and North Africa.
A peak of 2.2 million was reached in 2002. An estimated 1.8 million people died of AIDS in 2010.
Between 2001 and 2010, AIDS-related deaths increased more than 11-fold in Eastern Europe and Central Asia (from about 7,800 to 90,000), and more than doubled in East Asia (from 24,000 to 56,000), says the WHO.
In the Middle East and North Africa, AIDS-related mortality also increased by 60 percent (from 22,000 to 35.000).
By the end of 2010, 6.6 million people were taking antiretroviral drugs in low and middle income countries, or about 47 percent of the 14.2 million people whose immune systems were weakened to the point of needing therapy.
A new, updated figure is expected to be announced on July 18 by UNAIDS.
700,000 AIDS-related deaths were prevented worldwide in 2010 by people taking combination antiretroviral therapy.
US HIV BAN
The last world AIDS conference to take place in the United States was in 1990 in San Francisco. A US ban on travel to the country by people with HIV kept the conference away. The ban was lifted by the US government in 2008 and 2009.
Sources: WHO Progress Report 2011: Global HIV/AIDS Response; Health Affairs magazine, article by Anthony Fauci and Gregory Folkers, July 2012.
Explore further: AIDS: HIV drugs boost prevention hopes