LOS ANGELES, Oct. 17 (Xinhua) -- U.S. teens between the ages of 15 and 19 have a higher rate of sexual transmitted diseases (STD) than any other age group, according to a new study.

    The study by the Public Health Institute Center for Research on Adolescent Health and Development also found half of all new HIV cases are black females 15 years of age or older and Hispanic teen pregnancy is 68 percent higher than the rate among non-Hispanic teens.

    In order to promote abstinence, a national campaign "Parents Speak Up" was underway, according to Los Angeles County Supervisor Yvonne B. Burke.

    Citing the study, Burke said the number of new STDs among California youth is greater than previously thought.

    He called for local participation in the national campaign designed to encourage parents to initiate conversations with their children about abstinence.

    James Bolden, press deputy for Burke, said, "We just can't be silent about what we're seeing. We have to encourage parents to talk to their children and tell them they face tremendous risks if involved with sex... (There's) nothing wrong today to say to young people to stay away (from sex)."

    "We approve of any effort that begins with abstinence and goes from there. But if you begin and end with abstinence you are putting young people's life in danger," she said.