New data indicate New York City residents are contracting the virus that causes AIDS at three times the national rate

The city health department said that almost 4,800 New Yorkers were infected with HIV in 2006. The number represents 72 in every 100,000 residents, compared to a national rate of 23 per 100,000. The figures are the first to pinpoint when people became infected, not just when they were diagnosed. Better blood tests have helped make that possible. Health officials attribute the city's relatively high rate of new infections to its large populations of gay men, blacks and other groups on whom HIV has traditionally taken a heavy toll.