An astonished Fields, 48 and single, immediately got herself and her daughter tested in the van and rounded up five more neighbors over two days.
One of the most ambitious campaigns in the United States to interrupt the spread of HIV in an entire community is unfolding in Southwest Philadelphia.
Volunteers have started going door-to-door and expect to continue for two years, aiming to test 12,000 people. There are billboards, church sermons, Twitter messages and outreach workers who are buttonholing people on the street. Free oral swab tests are offered in the mobile van, and fingerstick blood tests at a health center.
A fourth decade
"Basically, what I want to do is change the culture around testing so that everyone gets tested," said Amy Nunn, a Brown University researcher who studies health disparities and HIV risk and leads the project.
"We think that regardless of what you do or your sexual orientation, you are at higher risk simply because of where you live," she said. "Because there is more virus in your community."
Last week's International AIDS Conference in Washington included repeated calls to ramp up efforts to test people for HIV. The reason is simple.
As the AIDS pandemic enters its fourth decade, treatment with costly antiviral drugs has proven highly successful. Yet prevention has largely failed. New infections are continuing at 50,000 annually, more than half of them transmitted by people who don't know they are positive. Testing has become a key prevention strategy.
"If people know they are infected, they are less likely to engage in unprotected sex, and if they are treated, they are less infectious," said Kenneth Mayer, head of HIV prevention at Beth Israel Deaconess Medical Center in Boston.
The Centers for Disease Control and Prevention for several years has focused testing on high-risk groups defined by behavior or race, not locale. But those groups tend to be clumped in geographical "hot spots," said Susan Little, a professor of medicine at University of California, San Diego, who ran a testing effort focused on two zip codes there. Everyone in the community, where people tend to socialize, have sex, and marry, becomes the "collateral [damage] of HIV infection."
A testing 'net'
Philadelphia's epidemic, for example, is largely heterosexual. Even though the rate of new infections for blacks is nearly 10 times that for whites, most black women don't think they are at risk. Encircling a neighborhood with what Little calls a testing "net" could alert them.
In San Diego, eight people did the testing. Philadelphia is training 60 volunteers to do it, mainly students in medical and other health professions.
On a recent Saturday, a handful of two-person teams went up and down Kingsessing Avenue from 46th to 54th Street, and several blocks on each side. Each house got a blue door knocker: "Do One Thing. Get Tested." Most also got a knock on the door.
"Hi, how are you?" said Pooja Kothari, a recent graduate of Wharton and the University of Pennsylvania's nursing school. She moved into a conversation about HIV, and then: "Do you want to come get tested?"
A few blocks away, another team stopped 29-year-old William Knight on the sidewalk. He quickly agreed.
HIV testing coordinator Danielle M. Parks swabbed his gums and asked 57 questions - employment, insurance, why did you agree to a test, do you have a smartphone? - that will be used to evaluate the project, which is also a research study on how to design a model geographically based campaign.
Was he at risk of HIV?
"I would like to think I'm at low risk," Knight told her.
Previous test? "Last year."
Ever injected drugs? "No."
Unprotected sex with a man? "No."
With a woman? "Yes."
Sexual partners in last six months? "One."
"Because you had sex with someone without a condom in the last 30 days, your risk would not be that low," Parks told him.
After 20 minutes, she read the confidential result: Negative. Big sigh of relief.
For Nunn, the project began with data. "I got obsessed with maps," she said. Overlapping layers showed that Southwest Philadelphia was poor, black, and had few places to get tested.
About 1.6 percent of the people in zip code 19143 were living with HIV/AIDS in 2010 - somewhat above the city average (which is double the national rate), and similar to the country of Jamaica. But the actual number of people (1,014) was the highest for a zip code not skewed by data from a prison.
And residents were dying of AIDS, the disease caused by the HIV virus, at nearly twice the citywide rate.
"That tells me there is an unmet need for testing and care," said Nunn, who works in the infectious-diseases division at Miriam Hospital in Providence, R.I.
She knew that simply offering tests wouldn't be much of a draw, particularly in an African American community where AIDS stigma is high: "You have to stimulate the demand for testing first."
Since 2010, when she spearheaded a citywide HIV initiative among black clergy, she has conducted more than 100 research interviews with African American leaders, exploring how to mobilize a community to fight a disease.
Gilead Sciences, which makes a drug that two weeks ago became the first to be approved to prevent HIV, donated $300,000. Nunn hopes to raise $1 million more.
She created a partnership with the Health Annex, a local health center, to make HIV testing a routine part of every patient visit.
"It is not the easiest thing in the world to ask about an HIV test, especially when you have a 14-year-old in the room with a parent," said Annex director Emily Nichols, perhaps explaining why current federal guidelines - routine tests for everyone ages 13 to 64 - are widely ignored.
Half the patients say no; they go home with a card that encourages them to think about it.
Since March, the Annex has more than tripled its number of tests, which used to be given mainly to people in high-risk groups. Four have come back positive.
David Acosta, the city's HIV prevention coordinator, said he was intrigued by Nunn's plan to offer hepatitis C screening along with HIV. Bundling them could be a step toward making HIV testing part of the battery of routine health screenings rather than the exception that it is now, he said.
Six billboards to generate interest in testing - "Do One Thing, Change Everything" - went up this month, augmented by a website ( www.1nething.com) and a range of social media.
Fifty-seven people were tested (no positives) during the first four days on the van, which will move from block to block on Thursdays, Fridays, and Saturdays.
Beth Rutstein, an outreach worker who just finished her first year at Penn medical school, said she was surprised at how easy it was to spread the word around the neighborhood:
"People come out waving their cards: 'I'm negative! I'm negative! I'm going to show this to everybody I know!' "
Contact Don Sapatkin
at 215-854-2617 or firstname.lastname@example.org.