| Objective:Live bird retail markets are an important part of the store,evolution,and transmission of avian influenza virus(AIV).It is a high-risk place for human infection with avian influenza and has caused serious public health problems.In order to maintain public health safety,reduce the risk of human infection with avian influenza,and promote the transformation and upgrading of live poultry production and operation,as pilot work first,the government of Guangzhou launched a “centralized slaughtering,cold chain distribution,and fresh poultry meat product listing and marketing” of poultry in some regions in May 2014.At present,there are few research reports on the evaluation of fresh poultry meat product listing and marketing measures,and a few reported studies are only based on the short-term AIV surveillance of environmental object surface of markets,and lacked scientific data on long-term systematic monitoring of AIV on the surface of the object and the contamination of air AIV.The purpose of this study is to understand the contamination status of AIV(H5\H7\H9\Hmix)on the surface of environmental objects and air in the live bird retail markets and fresh poultry meat product markets in different seasons and different regions;Compare the differences in nucleic acid positive rates between the object surface and air of AIV and H5/H7/H9/Hmix in the live bird retail markets and the fresh poultry meat product markets,and evaluate the effect of fresh poultry meat product listing and marketing measures,provide a scientific evidence for the government to make a decision to further expand the restricted area for live poultry operations.Methods:From January to December 2018,object surface surveillance and air surveillance on the live bird retail markets and the fresh poultry meat product markets in Guangzhou were conducted.The stratified cluster sampling method was used to randomly select one live bird retail market and one fresh poultry meat product market in the jurisdiction of 190 community health service centers(township hospitals)in Guangzhou in object surface surveillance,the types of specimens collected on the surface of the object included: surface sewage,dirt buckets,bird cages,depilators,cutting board knives,freezer inner walls and poultry meat surfaces;Three markets each in Guangzhou's live bird retail markets and fresh poultry meat product markets was selected by convenient sampling method in air surveillance,the areas where air samples were collected include: live poultry storage area,live poultry slaughter and depilation area,fresh poultry product processing area,sales area and stall front passage area.The collected object surface specimens and air samples were detected by real-time polymerase chain reaction(RT-PCR),and the AIV nucleic acid positive specimens/samples were further tested for H5,H7,and H9 subtypes.The positive rates of AIV and its subtypes of object surface specimens and air samples with different characteristics were compared by using the test of ?(17)or fisher's exact probability method.Pairwise comparisons were performed using the Bonferroni method.Statistical analysis was carried out using SAS 9.4.Results:1.Results of detection of AIV in object surface specimens from live bird retail markets and fresh poultry meat product markets:(1)Live bird retail markets: A total of 7,580 object surface specimens were collected,among these specimens,there were 2,288 AIV positive specimens(30.18%),including H5 281(3.71%),H7 22(0.29%),H9 1,599(21.09%),and Hmix 190(2.51%).The highest AIV positive rate of object surface specimens was 35.03% in the first quarter,and the difference in positive rates between quarters was statistically significant(?(17)= 98.49,P <0.01).H5,H9,and Hmix all reached their highest values in the fourth quarter,and the H7 positive rate was at a lower level of each quarter.The positive rates of AIV to surface sewage specimens and depilators specimens were 36.76% and 35.09%,respectively,which are at a relatively high level,the positive rates of different types of object surface specimens were statistically significant(?(17)= 80.33,P <0.01).After a pairwise comparison,the positive rates of H5,H7,H9 and Hmix on depilators specimens were highest(P<0.005).(2)Fresh poultry meat product markets: A total of 6,100 object surface specimens were collected,among these specimens,there were 1,242 AIV positive specimens(20.36%),including H5 145(2.38%),H7 5(0.08%),H9 676(11.08%),and Hmix 63(1.03%).The AIV-positive rate(26.69%)of object surface specimens in the first quarter was higher than in the other quarters,and the difference in positive rates between quarters was statistically significant(?(17)= 159.03,P <0.01).The H5 positive rate was highest in the fourth quarter,the H9 positive rate was highest in the first quarter,and the detection rate of H7 positive specimens was low in each quarter.Surface sewage specimens had the highest AIV positive rate of 28.42%,the positive rate of different types of object surface specimens was statistically significant(?(17)=127.73,P <0.01).2.Results of detection of AIV in air samples from from live bird retail markets and fresh poultry meat product markets:(1)Live bird retail markets: A total of 288 air samples were collected,including 38 AIV positive samples(13.19%),H5 1(0.35%),H7 1(0.35%),H9 8(2.78%),and Hmix 0.The AIV-positive rate of air samples in the fourth quarter was the highest,being 25.00%,there was a statistically significant difference in the positive rates of each quarter(?(17)=21.71,P <0.01).The H5,H7,and H9 positive rates were highest in the first quarter.The AIV positive rate of air samples collected in the live bird inventory area was the highest(27.78%),and there was a statistically significant difference in the positive rate of samples from different regions(?(17)=29.47,P <0.01).H5 and H7 positives were detected only in live poultry slaughter and depilation area,and the pairwise comparison showed that the air samples in live poultry storage area had the highest H9 positive rate(P <0.008).(2)Fresh poultry meat product markets: A total of 288 air samples were collected,of which 12 were AIV-positive samples(4.17%),H5,H7,H9 and Hmix were all 0.The AIV positive rate of air samples in the first quarter(8.33%)was higher than the other quarters,and the difference in positive rates between quarters was statistically significant(P = 0.02).The positive rate of AIV in air samples collected in fresh poultry product processing area was the highest,being 9.38%.The positive rate of air samples in different regions was statistically significant(P = 0.01).3.Comparison of positive rates of AIV on object surface specimens and air samples of live bird retail markets and fresh poultry meat product markets: The overall AIV positive rate(30.18%)of object surface specimens of live bird retail market is higher than that of fresh poultry meat product markets(20.36%),the difference is statistically significant(?(17)=170.38,P <0.01);the positive rates of H5,H7,H9 and Hmix of object surface specimens of live bird retail markets were 3.71%,0.29%,21.09% and 2.51%,which were higher than 2.38%,0.08%,11.08% and 1.03% of the fresh poultry meat product markets,the differences were statistically significant(?(17)=19.82,7.44,244.442,and 40.45,all P <0.01).The overall AIV positive rate of air samples in the live bird retail markets(13.19%)was higher than that in fresh poultry meat product markets(4.17%),and the difference was statistically significant(?(17)=14.81,P <0.01);the positive rate of H9(2.78%)of air samples from the live bird retail markets was higher than that of the fresh poultry meat product markets(0%),and the difference was statistically significant(P <0.01),both H5 and H7 positives were detected in air samples from the live bird retail markets,but none were detected in the fresh poultry meat product markets.Conclusions:There is a seasonal difference in the AIV contamination situation in the live bird retail markets and the fresh poultry meat product markets,and the contamination in spring and winter is serious.It is necessary to focus on strengthening the AIV monitoring and evaluation of the environmental object surface and air in winter and spring,and to guide and urge markets managers to take relevant prevention and control measures.The positive rates of AIV and H5\H7\ H9 and Hmix of object surface specimens and air samples from live bird retail markets were higher than those from fresh poultry meat product markets,the implementation of fresh poultry meat product listing and marketing measures could effectively reduce the environmental object surface and air contamination of AIV.In addition,air AIV contamination in the live bird retail markets needs to be highly concerned.Increasing surveillance of airborne AIV is of great public health significance for the early warning and prevention and control of human infection with AIV?... |
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