Days after an elderly man died of the virus, Hong Kong today confirmed its second human case of bird flu this season. A 70-year-old man, who had traveled to the neighboring Chinese cities of Shenzhen and Zhongshan earlier in December, tested positive for the H7N9 strain of the virus.<br/><br/>Authorities are still investigating the source of the infection. Cases of bird flu were expected to increase in winter based on its seasonal pattern. Bird flu was first reported in humans in Hong Kong in 1997. In the past two years Bird Flu scares have resulted in mass culling of upto 20,000 birds in the city.