Surveillance results of avian influenza virus in external environment in Changshou District of Chongqing from 2012 to 2021
Objective To investigate the distribution of avian influenza virus in external environment in Changshou District of Chongqing from 2012 to 2021,and to provide evidence for prevention and control of human infection with avian influenza.Methods From 2012 to 2021,five types of samples were collected from 4 sites in the outer environment in Changshou District.The samples were detected by fluorescent quantitative PCR for influenza virus A,H5,H7 and H9 subtypes.Chi-squre test was used for ratio comparision,with the test leve α=0.05.Results From 2012 to 2021,there were 1 074 avian influenza samples collected from outside environment,and 202 were positive for influenza A virus,with a positive rate of 18.81％.No statistically significant difference was observed in the positive rate between the years(x2=6.835,P=0.650).H5 subtype accounted for 30.69％of the positive samples,H9 subtype accounted for 51.98％,and H5+H9 mixed type accounted for 13.37％of the positive samples.Among the four sites,only urban and rural live poultry markets were positive,the positive rate was 29.28％.The positive rate of the five types of environmental samples was statistically significant(x2=89.561,P＜0.001);the positive rate of avian influenza virus was the highest(35.09％)in washing poultry sewage,followed by wiping the surface of slaughtering or placing poultry meat board(30.20％).There was statistically significance of positive rate in different quarters(x2=13.312,P＜0.001).The highest positive rate was 25.00％in the third quarter,followed by 20.24％in the first quarter.Conclusions The existing monitoring data showed that the environment outside in the live poultry market was contaminated by influenza A virus for a long time in Changshou District.It is necessary to be vigilant about the possibility of human transmission of avian influenza virus caused by positive environment outside the live poultry market.
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