Ms. Jako, who is from Lake Oswego, a suburb of Portland, Ore., tested positive for H.I.V. eight years ago, when she was 18. Yet, the agency says, only a quarter of sexually active teen-agers have been tested. With few exceptions, the study found, young people believed that H.I.V. could not affect them. But most of the teen-agers said that, given the opportunity, they would be tested for the virus. It doesn't get asked all the time, but when it does, young people will say yes.
Authorities say that acting quickly is important.
For individuals who do not seek H.I.V. testing until they are experiencing symptoms of illness associated with H.I.V.-related diseases or AIDS itself, today's treatments cannot offer as much hope. The teen-agers favored H.I.V. testing in offices that provided confidential and inexpensive tests, the study reported. Many did not want their parents to know. Some of the teen-agers had called around for cost estimates for the H.I.V. test and given up because they thought they could not afford it and did not realize their other options, such as free testing in some cities. The teen-agers also were more likely to be tested by doctors and nurses who respected the fact that they were sexually active.