A Hong Kong school was closed on Friday after a dead bird found in the southern Chinese city was tested positive for the deadly H5 strain of the bird flu virus, health officials said. The closure came after the school clerk, a 48-year-old woman, picked up a sick black-headed gull at the school on Tuesday, which died the next day and was tested positive for the H5 strain, a health department spokesman said. She picked up the bird - a common winter visitor - without any protection and developed a fever, sore throat and diarrhoea but has tested negative for Influenza A (H5), a variant of bird flu. \'\'She has been cleared in the medical results we received today but tests on her 11-year-old son are still ongoing, with results expected to be released later Friday,\'\' said the spokesman. Meanwhile the veterinary authorities in Hong Kong have informed the World Organisation for Animal Health (OIE) of a new outbreak of highly pathogenic avian influenza (HPAI). The report, dated 12 December, covers a new outbreak of H5N1 avian flu on a farm in Yuen Long. It is reported that there were 67,968 chickens and 25,680 fertilized eggs on this index farm with compulsory avian influenza vaccination program and strict biosecurity measures in place. Unusual mortality was first noted in the 285 sentinel chickens on 8 December. Clinical signs observed included rales, dyspnoea, cyanosis and oedema of the comb and wattle with yellow creamy nasal discharge. Cloacal swabs and chicken carcasses were collected on the same day for laboratory testing. Culling of the chickens and eggs began on 9 December and finished on 10 December.(QNA) MD