China has slaughtered more than 13,000 birds after an outbreak of the deadly H5N1 bird flu virus was confirmed in the far west, state media said. The outbreak is the first reported among birds this year despite the deaths of five people from the virus. Eight people have contracted bird flu this year in China but no sick poultry have been found in the areas where the patients fell ill, despite inspections of hundreds of thousands of birds. The World Health Organization has said the lack of cases raises questions about the quality of China's surveillance system. China's Ministry of Agriculture said 519 fowl died and were confirmed as having the H5N1 strain of bird flu, the official Xinhua News Agency reported late Tuesday. The fowl died in Hetian prefecture, also known as Hotan, in Xinjiang, China's far western region that borders Pakistan and Afghanistan.