Analysis of surveillance results of avian influenza infection in Nansi lake area,Shandong province from 2023 to 2024
Objective To analyze avian influenza virus infections in migratory birds,poultry(farms and slaughterhouses)and surrounding populations in the Nansi lake area of Shandong province.Methods A total of 11 migratory bird speci-men sampling sites were set up in Rencheng district,Yutai county and Weishan county nature reserves in Jining city in the Nansi lake basin,and 596 fresh migratory bird fecal samples were collected from January 2023 to March 2024 during the migratory season;Four survey sites(Zoucheng,Jinxiang,Yanzhou and Wenshang)were selected in Jining city,and a total of 3 726 poultry specimens were collected from January 2010 to March 2024.From January 2023 to March 2024,a total of 687 exposed individuals from the lake area,104 occupationally exposed workers from live poultry markets,and 73 control individuals were included,and their serum specimens were collected.Fluorescence quantitative PCR was used to detect in-fluenza viruses in migratory birds and poultry specimens,and hemagglutination inhibition test was used to detect antibodies to different subtypes of influenza viruses in serum specimens.Results The prevalence of avian influenza virus in speci-mens from migratory birds was 2.3％(14/596).The prevalence of avian influenza virus in environmental specimens from live poultry markets was 9.0％(337/3 726),in which the prevalence against H5,H7,and H9 subtypes was 0.4％(14/3 726),0.4％(14/3 726),and 4.7％(174/3 726),respectively.Serological investigation showed that the residents living around the Nansi lake and the poultry-exposed workers had higher seroprevalence against H5N1 and H9N2 than that of the general control population.In particular,individuals with occupational exposure to poultry had a higher risk of infection with H9N2 avian influenza virus than the control group(OR=1.68,95％CI:1.239-2.994,P＜0.05).Conclusion The rate of positive detection for avian influenza virus in live poultry markets in the South Four Lakes area of Shandong Province is relatively high,with the H9 subtype accounting for the highest proportion;the risk of infection with H5 and H9 subtype influenza viruses among the local population and poultry-related occupational exposure groups is high.
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