Millions once bought sex in the narrow alleys of Kamathipura, a vast red-light district in Mumbai. But prostitutes with inexpensive mobile phones are luring customers elsewhere, and that is endangering the astonishing progress India has made against AIDS.Indeed, the recent closings of hundreds of ancient brothels, while something of an economic victory for prostitutes, may one day cost them, and many others, their lives."The place where sex happens turns out to be an important HIV prevention point," said Saggurti Niranjan, program associate of the Population Council. "And when we don't know where that is, we can't help stop the transmission."Cellphones, those tiny gateways to modernity, have recently allowed prostitutes to shed the shackles of brothel madams and strike out on their own. But that independence has made prostitutes far harder for government and safe-sex counsellors to trace. And without the advice and free condoms those counsellors provide, prostitutes and their customers are returning to dangerous ways.Studies show that prostitutes who rely on cellphones are more susceptible to HIV because they are far less likely than their brothel-based peers to require their clients to wear condoms. In interviews, prostitutes said they had surrendered some control in the bedroom in exchange for far more control over their incomes."Now, I get the full cash in my hand before we start," said Neelan, a prostitute with four children whose side business in sex work is unknown to her husband and neighbours. (Neelan is a professional name, not her real one.)"Earlier, if the customer got scared and didn't go all the way, the madam might not charge the full amount," she explained. "But if they back out now, I say that I have removed all my clothes and am going to keep the money."India has been the world's most surprising AIDS success story. Though infections did not appear in India until 1986, many predicted the nation would soon become the epidemic's focal point. In 2002, the CIA's National Intelligence Council predicted that India would have as many as 25 million AIDS cases by 2010. Instead, India now has about 1.5 million.An important reason the disease never took extensive hold in India is that most women here have fewer sexual partners than in many other developing countries. Just as important was an intensive effort underwritten by the World Bank and the Bill and Melinda Gates Foundation to target high-risk groups like prostitutes, gay men and intravenous drug users.But the Gates Foundation is now largely ending its oversight and support for AIDS prevention in India, just as efforts directed at prostitutes are becoming much more difficult. Experts say it is too early to identify how much HIV infections might rise."Nowadays, the mobility of sex workers is huge, and contacting them is very difficult," said Ashok Alexander, the former director in India of the Gates Foundation. "It's a totally different challenge, and the strategies will also have to change."An example of the strategies that had been working can be found in Delhi's red-light district on Garstin Bastion Road near the old Delhi railway station, where brothels have thrived since the 16th century. A walk through dark alleys, past blind beggars and up narrow, steep and deeply worn stone staircases brings customers into brightly lighted rooms teeming with scores of women brushing each other's hair, trying on new dresses, eating snacks, performing the latest Bollywood dances, tending small children and disappearing into tiny bedrooms with nervous men who come out moments later buttoning their trousers.A 2009 government survey found 2,000 prostitutes at Garstin Bastion (also known as GB) Road who served about 8,000 men a day. The government estimated that if it could deliver as many as 320,000 free condoms each month and train dozens of prostitutes to counsel safe-sex practices to their peers, AIDS infections could be significantly reduced. Instead of broadcasting safe-sex messages across the country - an expensive and inefficient strategy commonly employed in much of the world - it encircled Garstin Bastion with a firebreak of posters with messages like "Don't take a risk, use a condom" and "When a condom is in, risk is out."Surprising many international AIDS experts, these and related tactics worked. Studies showed that condom use among clients of prostitutes soared."To the credit of the Indian strategists, their focus on these high-risk groups paid off," said Dr. Peter Piot, the former executive director of U.N. AIDS and now director of the London School of Hygiene and Tropical Medicine. A number of other countries, following India's example, have achieved impressive results over the past decade as well, according to the latest U.N. report, which was released last week.But now that mobile phones are untethering prostitution from brothels, those targeted measures are threatened. At the same time, the advent of cellphones seems to be expanding the sex marketplace - luring more women into part-time sex work and persuading more men to pay for sex. Cellphone-based massage and escort services are mushrooming across India."There may now be clients who may not have otherwise availed themselves of the services but do so now because it is easier and more private," said Suneeta Krishnan, a senior epidemiologist with Research Triangle Institute of North Carolina.The changes have led to a steep drop in business on Delhi's Garstin Bastion Road and have nearly destroyed Mumbai's Kamathipura district, where brothels had thrived since the 18th century.Champa, a wrinkled madam with silver toe rings, bangles on her wrists and henna-dyed hair, has for 50 years owned a brothel in a narrow lane here. But like many other industries where information technology has undermined the role of middlemen between buyers and sellers, Champa's business is withering."It's the end of Kamathipura," Champa said with a resigned wave as she squatted on the floor of her entryway.She once had as many as 20 prostitutes living in her nine-bedroom brothel; she now has three, she said. Worse, at least from her point of view, the women working for her collect their own fees and offer her just $2 a day to rent one of her tiny bedrooms. As recently as five years ago, Champa - she has just one name - collected $2 for every client served.As Champa spoke, several garishly dressed young women walked through the brothel's tiny foyer to sweep and water the hard dirt floor just outside. The lane was teeming with labourers, uniformed schoolchildren, and veiled matrons. The prostitutes soon settled onto benches and teased the men getting haircuts at a nearby outdoor barbershop.There were once 75 brothels on this lane; now there are eight. Kamathipura had as many as 50,000 prostitutes in the 1990s but now has fewer than 5,000, according to city officials and nongovernmental organizations.Kamathipura's destruction is partly a tale of urban renewal. India's rapid development has turned former slums into sought-after addresses, and rising land values led many brothel owners to sell out.But just as important has been the spread of cellphones into the hands of nearly three out of four Indians. Five years ago, cellphones were still a middle-class accoutrement. Fierce competition led prices to plunge, and now even trash pickers and rickshaw drivers answer pocket phones.But not all has changed. Vicious madams still exist, human trafficking is still rampant, village girls are still duped into the trade, and some brothels still thrive. Most prostitutes are illiterate, come from lower castes and are poor. But cellphones have given them a measure of power they did not have before. "I'm happy that mobile phones are so popular and that I have this opportunity," said Kushi, a mother who got into secret, part-time prostitution after she left her abusive and alcoholic husband. (Kushi is her work name.) She has three to four clients a week and charges each about $20, she said, compared with a typical price of $4 in cheap brothels.

© 2012, The New York Times News Service

"Cellphones allow the women to keep much more of their money," Niranjan of the Population Council said. "But they make HIV prevention programs more challenging."