Epidemiological Investigations And Studies Of Highly Pathogenic Avian Influenza (H5N1) Among Population With Different Occupations And Natural Environment In Fuyang

Objective:This paper was made to provide scientific basis to formulate strategies of prevention and control as well as to alert pandemic influenza by investigating the distribution of the highly pathogenic avian flu virus (H5N1) in natural environment, studying the infectious sources of the virus, confirming the highly-infected factors, monitoring the infected population with occupational exposure and researching the subclinical infections.Methods: Natural environmental samples like water, poultry(including migratory birds) feces and cage surface were collected from such monitoring points as wholesale market of living poultry, farm produce fair or vegetable market in urban and rural areas, large-scale poultry breeding sites, backyard farms and slaughthouses in Yingshang county where witnessed human-infected H5N1. All samples were detected with the method of RT-PCR or Real-time PCR in terms of influenza virus nucleic acid A, of which the positive one will be further detected by Chinese CDC in terms of H5, H7, H9 and seperated in terms of virus. Sera that collected from the listed population would be detected with singal radical hemolysis(SRH) so as to detect the infection rate of H5N1 antibody.Results: 60 samples were collected in natural environment in May, July, and December 2009, 20 samples respectively, and detected with RT-PCR, 2 of which(3.33%), collected in July, was FluA positive with one in water and the other daubed in board and both of them weren't subtyped. 60 samples were collected in natural environment in January, April, and September 2010, 20 samples respectively, and detected with RT-PCR or Real-time PCR, 9 of which(15.00%) was FluA positive. Among these 9 samples, with no H7 type, 2 samples, one in water and the other daubed in board, are H5 positive, 5 samples, 2 of them daubed in chicken house, 2 in water and 1 daubed in board, are H9 positive, the rest 2 samples, one in water and the other daubed in board. Besides, 1 untyped among these samples was collected in September 2010, the other 8 were in January 2010. All samples above weren't successful in virus separation. 193 sera were collected from poultry workers in 2009, 10 of which (5.18%) were positive after detected with SRH with 3 positive out of 100 collected in May and 7 positive out of 93 collected in December. 196 sera were collected from poultry workers in 2010, 30 of which (15.31%) were positive after detected with SRH with 17 positive out of 100 collected in April and 13 positive out of 96 collected in October.Conclusion: The highly pathogenic H5N1 virus exsits in Fuyang natural environment. And the population exposed to poultry handling was infected by avian influenza subtype H5, which shows the existence of subclinical infection. The possible reason lies in human-infected H5 virus in natural environment.