BEIJING, March 14 (Xinhuanet) -- A new study released Thursday from U.S. Centers for Disease Control suggests that about one in four teenage girls in the U.S. have at least one sexually transmitted disease.

    The study analyzed data on 838 girls ages 14 to 19 who took part in a 2003-04 government health survey. Twenty-six percent of the samples, which officials said were nationally representative, had a sexually transmitted disease.

    The teens were tested for four of the most common infections: human papilloma virus, or HPV, which can cause cervical cancer and affected 18 percent of the teens studied; chlamydia, which affected 4 percent; trichomoniasis, 2.5 percent; and genital herpes, 2 percent.

    Researchers found that African-American girls are the most affected: Nearly 50 percent have an STD, compared with 20 percent of white teen girls.

    Only about half of the teens in the study acknowledged having sex. Some teens define sex as only intercourse, yet other types of intimate behavior including oral sex can spread some diseases, the researchers said.

    "What we found is alarming," said Dr. Sara Forhan, a researcher with the Centers for Disease Control and Prevention and the study's lead author. "This means that far too many young women are at risk for the serious health effects of untreated STDs, including infertility and cervical cancer."

    In 2005, the certers reported that slightly more than half of teenage girls and boys had engaged in oral sex, which carries the risk of herpes and HPV, among other infections. Still another survey disclosed this year that after 16 years of decline, the birthrate among 15- to 19-year-olds has started rising.

    The study is the first national snapshot of infection rates among teenage group.

    (Agencies)