HONG KONG, June 8 (Reuters) - A magpie found dead in a densely populated residential district of Hong Kong has tested positive for the H5N1 bird flu virus, the government said on Friday. It was the 17th bird to have been found with the virus this year, a phenomenon blamed on the wild bird trade and which a growing number of experts say must stop. The bird was found dead in Sha Tin in the New Territories, home to one of Hong Kong's two racecourses, on May 31. The confirmation comes as Malaysian authorities monitor five people with flu-like symptoms in hospital. The five had been living near the site of a bird flu outbreak. The virus has killed 188 people since late 2003 but experts fear it could start a pandemic and kill millions once it gains the ability to transmit efficiently from person to person.