Persons age 50 and older now represent 19 percent of US HIV/AIDS cases - the result both of patients living longer and of more older people being diagnosed. "Historically, when you looked at AIDS diagnoses, people 50 and older accounted for 10 percent of all diagnoses," said Diane Sublets, an associate professor of sociology at the University of North Carolina-Charlotte. Older people who resume dating after long marriages may be uneducated about sex and about HIV, she said, having come through school at a time when sex education was not offered.