HIV rate among U.S. injection drug users falls: CDC CHICAGO (Reuters) - HIV infections among injection drug users in the United States have fallen by half in the past decade, but HIV testing is also down and risky behaviors such as needle-sharing persist, raising worries that progress may be short-lived, U.S. health experts said on Thursday. A study by researchers at the U.S. Centers for Disease Control and Prevention based on a 2009 survey of 10,000 people from 20 urban areas found that 9 percent of IV drug users were infected with the human immunodeficiency virus or HIV, the virus that causes AIDS. That compared with a rate of 18 percent in the 1990s. "Despite the fact that we've seen declines in new HIV infections, a substantial number of IDUs (injection drug users) in major US cities are HIV-infected and their risk behavior remains fairly high," said Dr. Cyprian Wejnert, an epidemiologist at the CDC, whose study appears in the CDC's weekly report on death and disease. "We found 9 percent of IDUs were HIV-positive and nearly half of those were unaware of their infection," Wejnert said in a telephone interview. HIV rates have been falling in the United States, but pockets of infection continue to persist, especially in high-risk groups such as young people and men who have sex with men. The latest survey tested individuals for HIV and asked questions about their risk behaviors and use of HIV prevention services. It found about one third of injection drug users in the survey said they shared syringes, most said they had unprotected sex in the past year and more than half said they had more than one sexual partner. The study also found that rates of HIV testing in this at-risk population are falling. "While CDC recommends that individuals are tested for HIV at least annually, only 49 percent, less than half of those interviewed, reported being tested in the last 12 months," Wejnert said. That represents a significant drop from a survey done in 2005-2006, he said. Dr. Amy Lansky, deputy director in the Division of HIV/AIDS Prevention at CDC, said the findings will be used as CDC focuses its prevention efforts on high risk populations. "It's a really important part of understanding the leading edge of the epidemic," she said. "What the data from this report shows is we really do need to continue our efforts to expand HIV testing and improve testing," she said, adding that the CDC also needs to focus its prevention efforts on reaching more drug users. Such efforts include offering new sterile syringes, condoms, and substance abuse treatment. According to the CDC, 1.2 million Americans have HIV, and 1 in 5 U.S. adults with HIV do not know they are infected. Editing by Mohammad Zargham