May 06, 2009 - Haikou, Hainan, China - China must keep highly alert as it is still facing the threat from influenza A/H1N1, which has spread to more than 20 countries and regions. The agriculture authorities would tighten monitoring of pig farms, slaughterhouses and livestock markets. PICTURED: Chinese law enforcement officers stop a pig attempting to flee during an inspection to a private slaughterhouse in Haikou city, Hainan province.