Surveillance for avian influenza A virus in environments in Lishui, Zhejiang,2009-2015

Objective To understand the distribution of avian influenza A (H5, H7 and H9) viruses in environments in Lishui, Zhejiang province, and provide evidence for the prevention and control of human infection with avian influenza virus. Methods From 2009 to January 2015,the samples of poultry washing water, feces and cage surface smears were collected from the surveillance sites to detect nucleic acid of avian influenza virus with real-time PCR, and the positive samples were further detected for H5, H7 and H9 nucleic acid. Excel software was used to analyze the results statistically. Results Avian influenza viruses were detected in 28 out of 87 surveillance sites (32.18%), and the detection rate was highest in poultry slaughtering and processing sites (100.00%), followed by alive poultry markets (92.30%). The sample source specific detection rate was highest in the samples from poultry slaughtering and processing sites (46.34%), followed by that in the samples from alive poultry markets (23.54%), and lowest in the samples from poultry free ranging areas (1.25%). The viral nucleic acid detection rate of subtype H5, H7, H9 and other subtype was 0.99%, 4.08%,5.83% and 9.33% respectively, and all the H7 viruses belonged to H7N9. The sample specific detection rate was highest in poultry washing water (40.00%) and lowest in cage surface smears (12.07%), the average one was 19.37%. The detection rate of subtype H5 was higher in autumn than in other seasons, and the detection rate of subtype H7 was higher in spring and winter than in summer and autumn, meanwhile the detection rate of subtype H9 was lowest in spring and highest in winter. The detection rate of subtype H5 was lowest. Conclusion Avian influenza A virus subtype H5, H7 and H9 circulate in the environments, especially in alive poultry markets and poultry slaughtering and processing sites, and the risk of human infection exists in Lishui. It is necessary to take active measures to prevent and control human infection with avian influenza virus.