The 19th International AIDS Conference is happening this week here in Washington, DC, and as the Washington Post’s David Brown reminds us, it’s a very different gathering from one that took place in San Francisco in 1990, when HIV was a mystery and AIDS a death sentence. Today, AIDS is still a terrible disease, but better understanding of it has improved both interventions and attitudes. “The issue is no longer what to do but rather whom to do it for, where, how quickly and at what cost,” Brown writes. He offers this global snapshot:

Today, more than 8 million people in low- and middle-income countries are taking the medicines. That’s 54 percent of those who should be getting it, according to clinical guidelines drawn up by the World Health Organization.

Coverage in sub-Saharan Africa is 56 percent. (That is the region targeted by the President’s Emergency Plan for AIDS Relief, or PEPFAR, the five-year, $15 billion program that George W. Bush announced to astonished listeners in his 2003 State of the Union speech.) Coverage is higher in Latin America (70 percent), lower in Asia (40 percent) and much lower in Eastern Europe and Central Asia (23 percent) and the Middle East and North Africa (13 percent).

Less than 10 years ago, there were only 400,000 people in the developing world taking anti-retroviral drugs. The 20-fold increase has occurred with astonishing speed. In Africa, the number of people on therapy jumped 20 percent — from 5.1 million to 6.2 million — in 2011 alone. The Obama administration announced last week that PEPFAR is now treating 4.5 million people, a half-million more than in December.

Prevention is also making headway.

In 2011, 2.5 million people acquired HIV — one-fifth fewer than a decade earlier. Last year, 57 percent of pregnant HIV-positive women got anti-retroviral drugs to prevent transmitting the virus to their babies — a strategy that produced 24 percent fewer newborn infections than just two years earlier.

In the past few years, 1.3 million African men have been circumcised, which studies show reduces the risk of becoming infected. In 2010 there were 131,000 health facilities offering HIV testing and counseling, up from 107, 000 just a year before. Changes in sexual behavior driven by educational campaigns and condom use have prevented hundreds of thousands of new cases.

The very presence of this conference on US soil is a big deal. Until President Obama lifted a 25-year-old ban on HIV-positive non-residents entering the US, the idea of holding an international AIDS meeting here would’ve been a non-starter.

Washington, DC is a fitting site for the International AIDS Conference not only because it’s the US capital, but because 2.7% of our residents are HIV positive, when a prevalence of 1% is considered a severe epidemic. The 2.7% figure is higher than that of many other US cities, but it’s an improvement from 2009, when researchers reported that 3% of District residents had HIV or AIDS. In the New York Times, Donald G. McNeil Jr. reports on some of the things DC has done to improve prevention, detection, and treatment:

The District of Columbia is a microcosm of both the best and worst trends in modern AIDS prevention and treatment. Infection rates here were so bad that they were compared to those in Africa. But the city’s innovative new programs, like testing people at motor vehicle offices, have been paying off.

New cases have fallen to 835 from 1,103 in 2006. And the number of mothers who infected their babies shrank to zero in 2010 from nine in 2005.

“It’s a tale of two cities,” said Phill Wilson, executive director of the Black AIDS Institute. “You can see the epidemic as bad as it is anywhere around the globe, and you can see some of the best practices.” As such, he said, Washington is “the perfect city to have this conference in.”

A new political will is driving the city’s turnaround.

“D.C. used to be a bureaucratic nightmare,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, which is just three subway stops outside the city, in Bethesda, Md. When Adrian M. Fenty took office as the mayor of Washington in 2007, Dr. Fauci said, “it was a whole new morning in America.”

The change is evident on many fronts. The number of H.I.V. tests given has tripled to 122,000 a year, from 43,000 in 2007. The city gave away five million male and female condoms last year, 10 times as many as it did in 2007. More than 300,000 clean needles a year are given away, both to heroin users and to an even higher risk group: transgender prostitutes who inject hormones.

Patients are being found in earlier stages of their illness, when it is more treatable. And 89 percent of those who test positive see a doctor within three days. Under the city’s Red Carpet program, nonprofit organizations are paid to drive new patients to the doctor.

McNeil notes that varying effectiveness among the dozens of nonprofit groups that provide HIV/AIDS services is a weakness, and Caitlin Gibson’s Washington Post story about Metro TeenAIDS peer educators also highlights the ongoing difficulties for many of DC’s young people. Six local residents who gathered to write a play to perform at the conference had the following stories to tell:

Ky’Lend Adams, 17, wrote about a woman at church who was shunned by her community when it became known she was HIV positive: “No one would sit next to her. . . . Everyone kept their distance, like they’d die if they got close.”

Terra Moore, 25, told of the challenges of romance as a transgendered young adult: “I’m afraid to become intimate with anyone, which is a deal breaker for most men in the city.”

Angela Hughes, 19, questioned a public education system that doesn’t address sex until after most kids are already having it: “I didn’t take my first sexual-education class until 11th grade.”

All six have faced their own struggles, including Davina Smith, 23, who married at 16, had a daughter at 17 and split from her husband at 19.

The encouraging part of Gibson’s article is her description of Metro TeenAIDS’ work:

The staff of Metro TeenAIDS knows all about the impact of the virus in their community. The group’s 45 peer educators — young people between 14 and 20 who are employed and trained by MTA to conduct weekly community outreach — mostly hail from the District’s low-income neighborhoods. They are active in schools and community centers, on the Internet, on street corners. Many integrate their work into their personal lives, stopping by MTA’s Eastern Market headquarters to pick up pamphlets and condoms on the way to a party or a club. Last year the educators reached more than 28,000 teens and young adults, according to MTA.

Progress against AIDS isn’t as fast as we’d like it to be, but it’s happening — in DC and around the world.