We have the medical tools to effectively halt HIV transmission, so what’s keeping these tools out of the hands of doctors and aid workers in high-risk areas?

The 2014 International AIDS Conference begins Sunday and will highlight stark contrasts in the world of HIV prevention, research, and education. Over 14,000 guests, including more than 800 journalists, are expected to cover the conference, widely considered the most important annual public health meeting on the globe.

While Australia, the country hosting the conference, has seen great success as one of the first nations in the world to try a harm reduction approach to HIV prevention, some African nations are criminalizing homosexuality, hampering efforts to test and treat their citizens for HIV.

Anti-LGBT laws have “taken us back,” said Jennifer Kates, vice president and director of global health and HIV policy for the Kaiser Family Foundation, during an online news conference last week.

Chris Beyrer, president-elect of the International AIDS Society, agreed, saying Australia’s success “is a story that will be part of the background” as the conference attendees “address the pushback we’re having against the extension of treatment and care against those who really need it the most.”

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Scientific breakthroughs, particularly the idea of “treatment as prevention,” have made it possible to nearly halt the spread of HIV in some populations. Yet the message still isn’t being effectively delivered to some of the most at-risk people.

Treatment as prevention refers to scientific proof that people with HIV who regularly take antiretroviral medications can have viral loads so low that their transmission risk falls by 90 percent. Coupled with Truvada, a once-daily pill to prevent HIV infection, a new reality has emerged for combatting the pandemic.

“Those of us working on HIV have been very focused on how we take to scale the things that we know that work,” Kates said. “It’s still a big, big challenge. We have so much more we know that works today.”

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Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said during the press briefing that “we can without hyperbole show that we can actually sharply deflect the curve of HIV incidence” even without a vaccine or a cure. “It is very frustrating that when you have the tools in your hand and you know you can implement them, that you don’t implement them,” he said.

Fauci noted that universal treatment or prevention is not possible in all countries, nor even in all states and regions, but it is possible in some communities if these tools are used aggressively.

One obvious barrier to the utopia Fauci describes is financial — the enormous burden on health systems expected to pay for these long-term treatments is insurmountable for many. Another has less to do with money and more to do with stigma: HIV prevention experts struggle to reach many at risk-groups who may be marginalized by their own governments.

Both issues will be discussed at the conference this week. On Thursday, the Kaiser Family Foundation will release its annual report on donor and government funding to fight the HIV/AIDS pandemic. The U.S. funnels about $7 billion a year toward the effort, but cutbacks are expected.

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Fauci said the issue of countries receiving money from the U.S. President’s Emergency Plan for AIDS Relief (PEPFAR) will no doubt be discussed. He said there will be a “re-looking at the landscape on how to best spread the money and help countries doing a really good job on their own build up sustainable programs.”

The issue of how to test and treat at-risk groups, sometimes called implementation science, received the most scientific attention in submissions for this year’s conference, Beyrer said. Presentations will be given on how best to reach sex workers, injection drug users, and other groups traditionally neglected in research.

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