Yet more than 20,000 international HIV researchers and activists will gather in the US capital later this month with a sense of optimism not seen in many years - hope that it finally may be possible to dramatically stem the spread of the AIDS virus.
"We want to make sure we don't overpromise," Dr Anthony Fauci, the National Institutes of Health's infectious disease chief, told The Associated Press.
But, he said, "I think we are at a turning point."
The big new focus is on trying to get more people with HIV treated early, when they're first infected, instead of waiting until they're weakened or sick, as the world largely has done until now. Staying healthier also makes them less likely to infect others.
"It saves lives of people who are infected, and it saves lives of people by not allowing them to get infected," Fauci explained.
That's a tall order. But studies over the past two years have shown what Fauci calls "striking, sometimes breathtaking results," in preventing people at high risk of HIV from getting it in some of the hardest-hit countries, using this treatment-as-prevention and some other protections.
Now, as the International AIDS Conference returns to the US for the first time in 22 years, the question is whether the world will come up with the money and the know-how to put the best combinations of protections into practice, for AIDS-ravaged poor countries and hot spots in developed nations as well.
"We have the tools to make it happen," said Dr Elly Katabira, president of the International AIDS Society, which organizes the world's largest HIV conference, set for July 22-27.
He points to strides already in Botswana and Rwanda in increasing access to AIDS drugs.
But Fauci cautioned that moving those tools into everyday life is "a daunting challenge," given the costs of medications and the difficulty in getting people to take them for years despite poverty and other competing health and social problems.
In the US, part of that challenge is complacency. Despite 50,000 new HIV infections here every year, an AP-GfK poll finds that very few people in the United States worry about getting the virus.
Also, HIV increasingly is an epidemic of the poor, minorities and urban areas such as the District of Columbia, where the rate of infection rivals some developing countries.
The conference will spotlight this city's aggressive steps to fight back: A massive effort to find the undiagnosed, with routine testing in some hospitals, testing vans that roam the streets, even free tests at a Department of Motor Vehicles office, and then rapidly getting those patients into care.
"These are the true champions," Dr Mohammed Akhter, director of the city's health department, said of patients who faithfully take their medication.
"They're also protecting their community."
A few miles east of the Capitol and the tourist-clogged monuments, the Community Education Group's HIV testing van pulls into a parking lot in a low-income neighborhood with a particularly high infection rate. An incentive for the crowd at a nearby corner is the offer of a $10 supermarket gift card for getting tested.
Christopher Freeman, 23, is first in line. He was tested earlier this year and says showing off that official paper proclaiming him HIV-negative attracts "the ladies."
"Forget money, it's the best thing you can show them," he said.
But that test was months ago, and Freeman admits he seldom uses condoms. He climbs into the van and rubs a swab over his gums.
Twenty minutes later, he's back for the result: Good news - no HIV.
But counselor Amanda Matthews has Freeman go through a list of the risk factors; it's education to try to keep him and his future partners safe.
"Just try to get yourself in the habit of using condoms," she said.
"You say it's hard to use condoms but what if you do contract the virus? Then you've got to take medications every day."
Freeman waves his new test result with a grin, and walks off with a handful of free condoms.
At a nearby bus stop, counselor Laila Patrick encounters a little resistance while handing out condoms, when a woman says that encourages sex outside of marriage.
"Stopping AIDS is everyone's business. You're looking out for the next person," Patrick said.
"You might just want to help someone be safe."
Most new infections among gay and bisexual men in US
About 34 million people worldwide have HIV, including almost 1.2 million Americans. It's a very different epidemic from the last time the International AIDS Conference came to the United States, in 1990.
Life-saving drugs emerged a few years later, turning HIV from a death sentence into a manageable chronic disease for people and countries that can afford the medications.
Yet for all the improvements in HIV treatment, the rate of new infections in the US has held steady for about a decade. About 1 in 5 Americans with HIV don't know they have it, more than 200,000 people who unwittingly can spread the virus.
Government figures show most new US infections are among gay and bisexual men, followed by heterosexual black women. Of particular concern, African-Americans account for about 14% of the population but 44% of new HIV infections.
Where you live plays a role in your risk, too. Twelve cities account for more than 40 % of the nation's AIDS cases: New York, Los Angeles, Washington, Chicago, Atlanta, Miami, Philadelphia, Houston, San Francisco, Baltimore, Dallas and San Juan, Puerto Rico. Many are concentrated in specific parts of those cities.
"Maps tell the story," said Brown University assistant professor Amy Nunn, who is beginning a campaign that will bring a testing van door-to-door in the hardest-hit areas of Philidelphia.
"It's not just what you do, it's also where you live. There's just a higher chance that you will come into contact with the virus," she explained.
Prospects for a vaccine are so far elusive and health disparities are widening, so why the optimism as expressed by the Obama administration's goal of getting to an AIDS-free generation?
Consider the potential strategies, to add to tried-and-true steps such as condom use and treating HIV-infected pregnant women to protect their unborn babies:
-Studies found treatment-as-prevention could lower an HIV patient's chance of spreading the virus to an uninfected sexual partner by a stunning 96%. In the US, new guidelines recommend starting treatment early rather than waiting until the immune system has weakened. Abroad, the United Nations hopes to more than double the number of patients being treated in poor countries to 15 million by 2015.
-Other studies show a longtime AIDS medication named Truvada can prevent infection, too, if taken daily by healthy people who are at risk from their infected sexual partners. The US Food and Drug Administration is expected to decide by fall whether to formally approve sale of Truvada as an HIV preventive.
-A study from South Africa found a vaginal gel containing anti-AIDS medication helped protect women when their infected partners wouldn't use a condom, generating more interest in developing women-controlled protection.
-Globally, experts also stress male circumcision, to lower men's risk of heterosexually acquired HIV.
What adults say
Testing is a key step in improving prevention. The AP-GfK poll found 57% of adults say they've been tested at some point, a bit higher than federal estimates, but not enough. The government recommends at least one test for adults, and that populations at higher risk get tested at least once a year.
Following those recommendations depends in part on people's concern about AIDS. The poll found just over half of Americans consider HIV as much or more of a problem now than two decades ago.
But less than 20% are worried about getting it themselves, and even populations at higher risk don't consider HIV a big threat. Some 16% of black respondents said they're very worried about HIV, compared with 4% of whites.
"We've become complacent about HIV in America, and it's a real tragedy because hundreds of thousands of people in our own country aren't getting the care they need," said Chris Collins of amFAR, The Foundation for AIDS Research.
The drugs can cost up to $15,000 a year in the US, and overall treatment costs are rising as people with HIV live longer. In developing countries, those drugs can cost less than $400 a year.
The AP-GfK Poll was conducted June 14-18 by GfK Roper Public Affairs and Corporate Communications.
It involved landline and cellphone interviews with 1,007 adults nationwide. Results for the full sample have a margin of sampling error of plus or minus 4.0 percentage points.
In the US, the government is targeting the hardest-hit communities as part of a plan to reduce HIV infections by 25% by 2015, said assistant secretary of Health Howard Koh.
Work is under way to learn the best steps to get people treated early, including in cities such as Washington, where 2.7% of residents have HIV, roughly four times the national rate.
Washington resident Zee Turner knows it's hard to stick with care. She's had HIV for two decades, learning the news when her baby was born sick. Health workers helped mom and daughter receive then-newly emerging treatments, and they're doing well today.
"I felt that I should get out here and try to help somebody else, because somebody had to help us get into care," said Turner, now 53 and a community health worker.
The city's latest HIV count suggests progress, with a slight decrease in new diagnoses and a majority of patients being connected with medical care. Community workers such as Turner are called to try to help people stay on treatment when other problems intervene.
"If they're on drugs, I take them to the drug program. If they need help going on Medicaid, I go with them to Medicaid," Turner said.
"Any problem they have, I'm going to try to fix it and get them back into care."