More men in their 20s were infected with HIV through same-sex encounters last year, according to government statistics, in a trend health experts said was alarming. In the first major increase since the city began keeping track in 1985, the number of men who contracted HIV, the virus that causes Aids, through same-sex encounters were aged between 20 and 29. Their age group saw 164 new infections last year, compared to those aged 30 to 39, who usually have the most new infections but saw 102 new cases last year, Health Department figures showed yesterday. Dr Wong Ka-hing, consultant in the special preventive programme at the Health Department, said sexual encounters between men accounted for the majority of new HIV infections and Aids cases worldwide. Hong Kong keeps with that trend, as 378 of the 651 new cases reported in 2014 were transmitted via sexual encounters between men. In just the last quarter of 2014, the city saw 152 new cases, 125 of which occurred in men. Of those, 82 were acquired via homosexual or bisexual sex. "The trend [of a younger infected population] is worrisome … the situation will only get worse for them. With more people infected in the community, the chance of getting infected also increases," he said. Those infected younger will also have to live with the virus longer. He said that despite this being the "information age", young people's knowledge of HIV and Aids had declined. He cited social workers who said they seemed even less aware than in years past about the dangers and protection measures. "Obviously, I don't think current prevention [measures] have been successful," Wong said, referring to the steadily increasing overall infection rate. Wong said a 2011 study of men who have sex with men showed an infection rate around 4 per cent, but that had increased to 6 per cent this year. He said Hong Kong needed to do better at diagnosing cases, and called for the homosexual and bisexual community to make promoting HIV and Aids awareness a top priority. The outreach group Aids Concern said stigma and discrimination kept a lot of young gay or bisexual men from getting tested for fear of exposing their sexual orientation. Since the first HIV case was detected in 1985, Hong Kong has recorded 6,993 such cases, with 1,545 developing into Aids.