H5N1 avian influenza, known commonly as bird flu, has killed at least 15 people across Asia and was confirmed in China on January 27. No human cases have been found in the mainland, but 13 of the country's 31 provinces, autonomous regions, and municipalities (直辖市) have reported the disease in poultry. The Chinese government has taken measures to prevent and control the disease. Poultry within 3 km of infected farms is to be killed and those within 5 km vaccinated (进行接种疫苗 ). Meanwhile, there will be constant monitoring and daily reports on the disease across the country, and increased production of bird flu vaccines. Among the Asian countries and regions affected by bird flu in animals, only Vietnam and Thailand have reported human cases. The people infected were reported to have caught the disease from poultry. While the World Health Organization (WHO) said there is 'no proof of human-to-human transmission (传播)' of bird flu. The big fear is that the disease could combine with a human influenza virus (病毒) to create a deadly new disease that will kill millions of people across the globe. Many Asian farmers live closely with their animals and sell live chickens in the market. This greatly increases the possibility of human beings infected with bird flu. A spokesman of the WHO said that Asian countries affected by bird flu should introduce a more healthy way of raising and selling chickens. And the people there have to completely change their lifestyle. and attitude towards animals. Here are some safety measures for people to stay healthy: Keep fit and well through regular exercise Avoid infected poultry and infected people Avoid eating raw or under-done poultry and eggs Make sure there is always fresh air in your home Cover your mouth and nose when coughing or sneezing Wash your hands frequently. What does the underlined word 'poultry' mean?