Résumé
Objective:To analyze the genetic evolution and molecular characteristics of H5N8 avian influenza viruses (AIVs) isolated from the poultry in a live poultry market (LPM) in Urumqi, Xinjiang.Methods:Oropharyngeal and cloacal swabs of poultry were collected from a LPM in Urumqi in 2016. AIVs were isolated by inoculating swab samples into chicken embryos. Hemagglutination test and RT-PCR were used to identify the AIVs. The genes of isolated AIVs were amplified with the universal primers of AIV and whole-genome sequencing was also performed. Pairwise sequence alignment and analysis of phylogenetic and molecular characteristics were performed using BLAST, Clustal W, MEGA-X and DNAStar software.Results:Five H5N8 AIVs were isolated from poultry. These strains shared a nucleotide identity of 99.70%-100.00%, which indicated that they were from the same source, and were named XJ-H5N8/2016. Phylogenetic analysis based on hemagglutinin( HA), NS and PB2 genes showed that these isolates were clustered together with H5N8 AIVs isolated from the migratory swans in Hubei, Shanxi and Sanmenxia, and the ducks in India during 2016 to 2017. Moreover, they were also clustered together with H5N6 AIVs isolated from minks in China and the first case of human infection in Fujian. The phylogenetic tree of neuraminidase( NA) gene indicated the five isolates clustered together with H5N8 AIVs isolated from ducks in India in 2016, and the phylogenetic trees of PB1, MP, PA and NP genes showed that they were clustered together with H5N8 AIVs isolated from wild birds and poultry in Egypt, Cameroon, Uganda, Congo and other African countries in 2017. The HA cleavage sites of XJ-H5N8/2016 contained five consecutive basic amino acids, indicating high pathogenicity. Multiple mutations in the genes of XJ-H5N8/2016 could enhance its virulence and pathogenicity to mammals. Conclusions:The five strains of H5N8 AIVs isolated from the LPM were highly pathogenic and closely related to the H5N8 AIVs isolated from migratory birds and poultry in Hubei, Shanxi, Sanmenxia area, Africa and India during 2016 to 2017. Meanwhile, some of the viral genes were also closely related to the H5N6 AIVs isolated from the minks and human in China. Multiple mutations could increase the virulence and pathogenicity of AIVs to mammals, which could pose a potential threat to public health.
Résumé
Objective To explore the source of human infection H9N2 avian influenza virus (AIV). Methods Environmental AIV nucleic acid monitoring was conducted for live poultry markets in Changsha city from 2014 to 2015, and data of human infection H9N2 subtype AIV cases worldwide were collected. Phylogenetic trees of hemagglutinin(HA), neuraminidase(NA)and non-structural protein(NS)genes from human infection H9N2 subtype AIV, the live poultry markets environmental H9N2 subtype AIV and partial avian H9N2 subtype AIV were constructed using the MEGA 6.06 software, respectively. Results In 2014-2015, H9 subtype AIV had the highest nucleic acid positive rate (44.76%) in the live poultry markets environment of Changsha city, and the pollution was serious. A total of 27 cases of human infection with H9N2 subtype AIV had been reported worldwide, and most of these patients recovered after treatments.Epidemiological survey showed that 59.26% (16/27) of cases had a clear history of exposure to poultry or live poultry markets. The phylogenetic trees of HA, NA and NS genes showed that the human infection H9N2 subtype AIV isolates isolated from Hunan and Guangdong were closely related to the H9N2 subtype AIV isolated from the live poultry markets environment in Hunan and Guangdong provinces from 2013 to 2016. The nucleotide similarity was as high as 97%-99%. Conclusion Live poultry market is one of the sources of human infection with H9N2 influenza virus.
Résumé
Short-term closing live poultry markets have been frequently adopted to control H7N9 epidemic.To evaluate the effect of short-term closing live poultry markets,we analyzed the data of environment surveillance of H7 by RT-PCR,and the human H7N9 cases in Zhongshan City from Feb 2014 to May 2017.RRx =The positive rate during the x-th week after closing / the positive rate of the week before closing days * 100％.Three rounds of short-term closing live poultry markets were administered.Round one:from Feb 10 to 23,2014,the neighboring cities didn't synchronize.The H7 positive rate increased since the trade recovered,and RR1 =0.40 (95％CI:0.28-0.59),RR3 =0.63 (95％CI:0.32-1.24),RR4 =0.83 (95％CI:0.48 -1.46).Two human cases were reported in May,2014.Round two:from Feb 19 to 28,2015,the neighboring cities synchronized as the province policy.The H7 positive rate maintained a level lower than 10％ since the trade recovered,and RR1 =0.15 (95％CI:0.07-0.34),RR2=0.21 (95％CI:0.10-0.41),RR3 =0.03 (95％CI:0.00-0.18),RR4 =0.10 (95％CI:0.04-0.27).No more human cases reported in that epidemic season.Round three:from Jan 8 to 21,2017,the neighboring cities didn't synchronize with Zhongshan City.The H7 positive rate had increased since the trade recovered,and RR1 =0.25 (95 ％ CI:0.09-0.68),RR3 =0.37 (95％CI:0.14-1.00),RR4 =1.07 (95％CI:0.54-2.11).Two human cases were reported in Feb,2017.Results indicated that,if the policy of closing live poultry markets was administered in single city,the environment pollution rate would rise shortly and the risk of human infection would increase once the trade recovered.However,if it was synchronously administered in all the cities in one region,the environment pollution rate could maintain at a low level and the risk of human infection would reduce enormously.
Résumé
Due to adverse economic impact and social panic influences,live poultry market closure(LPM) as an effective control strategy of H7N9 influenza has become the focus of public repeatedly.So this paper reviewed transmission characteris tics of H7N9 influenza,impact of LMP on human H7N9 infection,and the effect of LMP on H7N9 influenza control.
Résumé
Objective To investigate the distribution of avian influenza A viruses in external environment in Urumqi City in order to provide reference for the prevention and control of human infection with avian influenza virus in Urumqi City.Methods Environmental specimens were collected from 2013 to 2015 to detect avian influenza A virus nucleic acid with real-time fluorescent PCR.The positive specimens were further analyzed to identify the subtypes of avian influenza A viruses.Results A total of 1 043 environmental specimens were collected and tested.Among them,123 specimens were positive for avian influenza A virus nucleic acid with an overall positive rate of 11.79%.H9 was the predominant subtype,accounting for 7.77% of all specimens.Quarterly detection rates of avian influenza A virus in the three years peaked in different quarters of the year.Of all surveillance sites,live poultry markets in urban and rural areas had the highest positive rate (14.23%).Specimens collected from poultry drinking water (18.44%) and other specimens (19.44%) were highly positive for avian influenza A virus.Conclusion Avian influenza A viruses,especially the subtypes of H5,H7 and H9,exist in live poultry markets in Urumqi City.It is necessary to conduct surveillance and health education among people exposed to poultry in live poultry markets.
Résumé
Since March 2013,China had experienced five seasonal epidemics related to Avian influenza A (H7N9).An unprecedented outbreak of H7N9 epidemic started from September 2016,with 730 cases reported till June 30th 2017,in mainland China that caused profound influences on both social development and health of the people.As an emerging infectious disease,information on pathogenic characteristics,transmission patterns and other epidemiological features of H7N9 virus somehow remained unclear.Data from previous studies suggested that the live poultry market (LPM) seemed to have served as main places where H7N9 virus got originated,mutated,spread and thus infected the human beings.Hence,closure of LPMs was suggested a major measure to control and prevent H7N9 epidemics in China.However,the effectiveness of different ways of LPM closures on H7N9 epidemics had been controversial.This study systemically summarized the effects of different ways of LPM closures on H7N epidemics from previous studies,aiming to provide references for developing a better program on H7N9 control and prevention in the country.
Résumé
Since March 2013,China had experienced five seasonal epidemics related to Avian influenza A (H7N9).An unprecedented outbreak of H7N9 epidemic started from September 2016,with 730 cases reported till June 30th 2017,in mainland China that caused profound influences on both social development and health of the people.As an emerging infectious disease,information on pathogenic characteristics,transmission patterns and other epidemiological features of H7N9 virus somehow remained unclear.Data from previous studies suggested that the live poultry market (LPM) seemed to have served as main places where H7N9 virus got originated,mutated,spread and thus infected the human beings.Hence,closure of LPMs was suggested a major measure to control and prevent H7N9 epidemics in China.However,the effectiveness of different ways of LPM closures on H7N9 epidemics had been controversial.This study systemically summarized the effects of different ways of LPM closures on H7N epidemics from previous studies,aiming to provide references for developing a better program on H7N9 control and prevention in the country.