A dead grey heron found in Lok Ma Chau has tested positive for the bird flu virus but the Health Authority yesterday said there was no sign of an outbreak in Hong Kong. Lau Sin-pang, acting director of agriculture, fisheries and conservation, said laboratory tests confirmed the heron, found by a railway worker on Monday, carried the H5N1 strain of bird flu. The department inspected 37 chicken farms near the site but found no suspicious deaths. Mr Lau said the department had increased the frequency of inspections at these farms from once every two weeks to once a week. Farmers have been reminded to strengthen bio-security measures and report any suspicious deaths to the department immediately. Centre for Health Protection consultant Thomas Tsang Ho-fai said seven people who had had contact with the heron had been placed under medical observation for a week. He said they were all in good health. The centre had been contacting them every day by phone to check on their condition. The heron is the second bird found with the H5N1 virus in Hong Kong this year. In January, a dead peregrine falcon found near the Gold Coast residential development in Tuen Mun also tested positive for the virus. Outbreaks of H5N1 have killed 32 people in Thailand and Vietnam this year and prompted poultry culls across Southeast Asia. In Hong Kong, a bird flu outbreak infected 18 people in 1997, killing six.