Live Poultry Markets Research Articles

Development and evaluation of a real-time RT-PCR assay for detection of a novel avian influenza A (H5N6) virus

As of Aug 25, 2017, 17 incidences of human infection and 6 deaths due to the novel H5N6 virus have been reported in China. Genetic analysis of the viral genome revealed that this reassortant virus is highly pathogenic to poultry, and that the virus has a risk of transmission to humans. Accordingly, the development of a rapid, sensitive, and specific molecular diagnostic assay is critical for public health. In this study, a real-time reverse-transcription PCR (RT-PCR) assay was developed to specifically detect the novel H5N6 virus, with primer pairs targeting the hemagglutinin and neuraminidase gene sequences of this virus. RNA was extracted from throat swab specimens from patients with influenza-like illness (ILIs), and environmental samples were collected from live poultry markets (LPMs) for H5N6 virus detection by real-time RT-PCR. The method was demonstrated to enable specific detection of the avian H5N6 virus, with no cross-reactivity with seasonal influenza viruses (H1N1, H1N1 pdm09, H3N2 or B); H5N1, H7N9, H9N2 viruses; or other human respiratory viruses. The detection limit of the assay was 1.0 × 101 copies per reaction for N6 and 1.0 × 102 copies per reaction for H5 assays. The assay is a powerful tool for rapid, sensitive, and specific detection of H5N6 virus infection in specimens derived from humans, animals, and the environment.

Comparison of the three waves of avian influenza A(H7N9) virus circulation since live poultry markets were permanently closed in the main urban areas in Zhejiang Province, July 2014-June 2017.

BackgroundThe sudden increase in the number of human cases infected with avian influenza A(H7N9) virus after September 2016 raised global concern.ObjectivesTo assess the changes in epidemiological characteristics of H7N9 cases since the massive closure of live poultry markets (LPMs) in the main urban areas in Zhejiang province.MethodsWe used descriptive statistics to compare epidemiological characteristics of the three distinct waves of H7N9 cases in Zhejiang province. The rural or urban cases were defined according to the location where the patients had exposure within 2 weeks before illness onset.ResultsBetween July 2014 and June 2017, 166 H7N9 cases were reported in Zhejiang province, with 45, 34, and 87 cases reported in the third, fourth, and fifth wave, respectively. Across the three waves, most reported cases were from rural areas. A similar percentage of cases in all three waves reported exposure to LPMs, raising poultry at home or around the house, as well as occupational exposure. Compared to the third (80.00%) and fourth wave (70.59%), a significantly larger proportion of cases from the non‐LPMs closure areas were observed in the fifth wave (89.66%) (P = .034).ConclusionEpidemiological characteristics of human cases infected with avian influenza A(H7N9) virus had generally remained unchanged since the massive closure of LPMs in the main urban area of Zhejiang province. The sudden increase in the number of H7N9 cases in the fifth wave was mainly attributed to the excessive cases reported from areas where LPMs were not permanently closed.

An increasing trend of rural infections of human influenza A (H7N9) from 2013 to 2017: A retrospective analysis of patient exposure histories in Zhejiang province, China.

BackgroundAlthough investigations have shown that closing live poultry markets (LPMs) is highly effective in controlling human influenza A (H7N9) infections, many of the urban LPMs were shut down, but rural LPMs remained open. This study aimed to compare the proportional changes between urban and rural infections in the Zhejiang province from 2013 to 2017 by analyzing the exposure histories of human cases.MethodsAll laboratory-confirmed cases of H7N9 from 2013 (the first wave) to 2017 (the fifth wave) in the Zhejiang province of China were analyzed. Urban and rural infections were defined based on the locations of poultry exposure (direct and indirect) in urban areas (central towns) and rural areas (towns and villages on the outskirts of cities). A Chi-square trend test was used to compare the proportional trend between urban and rural infections over time and logistic regression was used to obtain the odds ratio by years.ResultsFrom 2013 to 2017, a statistically significant trend in rural infections was observed (p <0.01). The incremental odds ratio by years of rural infections was 1.59 with 95% confidence intervals of 1.34 to 1.86. Each year, significant increases in the proportion of live poultry transactions in LPMS and poultry processing plants were detected in conjunction with an increased proportion of urban and rural infections.ConclusionThe empirical evidence indicated a need for heightened infection control measures in rural areas, such as serving rural farms and backyards as active surveillance points for the H7N9 virus. Other potential interventions such as the vaccination of poultry and extending the closure of LPMs to the provincial level require further careful investigations.

Contact reductions from live poultry market closures limit the epidemic of human infections with H7N9 influenza

An early steep increase in the number of humans infected with avian influenza A(H7N9) virus was observed in China, raising great public concern domestically and internationally. Little is known about the dynamics of the transmission contacts between poultry and human populations, although such understanding is essential for developing effective strategies to control this zoonosis. In this study, we evaluated the effects of contact reductions from live poultry markets (LPMs) closures on the transmission of H7N9 virus during epidemics in Guangdong Province, China. A mathematical model of the poultry-to-person transmission dynamics of H7N9 virus was constructed. The parameters in the model were estimated from publicly available data on confirmed cases of human infection and information on LPMs closure during 2013–2017. By fitting the model, we measured the time-dependent contact quantity of the susceptible population to LPMs. The results showed that periodic intervention strategies can greatly reduce the magnitude of outbreaks, and the earlier interventions for policy are implemented, the smaller is the outbreak. The control efforts for LPMs to decrease the contact quantity are critical in preventing epidemics in the long term. This model should provide important insights for the development of a national intervention strategy for the long-term control of avian influenza virus epidemics.

Evaluation of animal-to-human and human-to-human transmission of influenza A (H7N9) virus in China, 2013\u201315

A novel avian-origin influenza A(H7N9) virus emerged in China in March 2013 and by 27 September 2017 a total of 1533 laboratory-confirmed cases have been reported. Occurrences of animal-to-human and human-to-human transmission have been previously identified, and the force of human-to-human transmission is an important component of risk assessment. In this study, we constructed an ecological model to evaluate the animal-to-human and human-to-human transmission of H7N9 during the first three epidemic waves in spring 2013, winter/spring 2013–2014 and winter/spring 2014–2015 in China based on 149 laboratory-confirmed urban cases. Our analysis of patterns in incidence in major cities allowed us to estimate a mean incubation period in humans of 2.6 days (95% credibility interval, CrI: 1.4–3.1) and an effective reproduction number Re of 0.23 (95% CrI: 0.05–0.47) for the first wave, 0.16 (95% CrI: 0.01–0.41) for the second wave, and 0.16 (95% CrI: 0.01–0.45) for the third wave without a significant difference between waves. There was a significant decrease in the incidence of H7N9 cases after live poultry market closures in various major cities. Our analytic framework can be used for continued assessment of the risk of human to human transmission of A(H7N9) virus as human infections continue to occur in China.

The molecular characteristics of avian influenza viruses (H9N2) derived from air samples in live poultry markets

ObjectiveTo study the molecular characteristics of H9N2-subtype avian influenza viruses (AIVs) isolated from air samples collected in live poultry markets (LPMs) and explore their sequence identities with AIVs that caused human infection. MethodsWeekly surveillance of H9N2-subtype AIVs in the air of LPMs was conducted from 2015 to 2016. H9-positive samples were isolated from chicken embryos. Whole genome sequences of the isolated AIVs were obtained through high-throughput sequencing. Phylogenetic analysis and key loci variations of the sequences were further analyzed. ResultsA total of 327 aerosol samples were collected from LPMs. Nine samples were positive for H9-subtype AIVs based on quantitative real-time reverse transcription polymerase chain reaction (qRRT-PCR). According to the whole genome sequence analysis and phylogenetic analysis, except for the A/Environment/Zhongshan/ZS201505/2015 (ZS201505) strain, 8 gene segments of 8 aerosol H9N2 isolates and 2 H9N2 human isolates in 2015 were located in the same clade. Among key loci variations, except for the ZS201505 strain, H9N2-subtype AIVs had no mutations in eight receptor binding sites of hemagglutinin (HA), and stalks of neuraminidase (NA) proteins exhibited a deletion site of three bases. The PA gene of ZS201503 and ZS201602 exhibited an L336M mutation. The N30D and T215A mutations in the M1 gene and amino acid residues L89V in PB2, P42S in NS1 and S31N in M2 were retained in these 9 strains of H9N2 isolates, which could enhance the virus's virulence. ConclusionLive H9N2 AIVs survived in the aerosol of LPMs in Zhongshan City. The aerosol viruses had a close evolutionary relationship with human epidemic strains, indicating that there might be a risk of AIV transmission from polluted aerosols in LPMs to humans. Mutations in H9N2-subtype AIVs isolated from air samples collected from LPMs suggested their pathogenicity was enhanced to infect humans.

Novel reassortant H5N6 highly pathogenic influenza A viruses in Vietnamese quail outbreaks.

Avian influenza A H5N6 virus is a highly contagious infectious agent that affects domestic poultry and humans in South Asian countries. Vietnam may be an evolutionary hotspot for influenza viruses and therefore could serve as a source of pandemic strains. In 2015, two novel reassortant H5N6 influenza viruses designated as A/quail/Vietnam/CVVI01/2015 and A/quail/Vietnam/CVVI03/2015 were isolated from dead quails during avian influenza outbreaks in central Vietnam, and the whole genome sequences were analyzed. The genetic analysis indicated that hemagglutinin, neuraminidase, and polymerase basic protein 2 genes of the two H5N6 viruses are most closely related to an H5N2 virus (A/chicken/Zhejiang/727079/2014) and H10N6 virus (A/chicken/Jiangxi/12782/2014) from China and an H6N6 virus (A/duck/Yamagata/061004/2014) from Japan. The HA gene of the isolates belongs to clade 2.3.4.4, which caused human fatalities in China during 2014-2016. The five other internal genes showed high identity to an H5N2 virus (A/chicken/Heilongjiang/S7/2014) from China. A whole-genome phylogenetic analysis revealed that these two outbreak strains are novel H6N6-like PB2 gene reassortants that are most closely related to influenza virus strain A/environment/Guangdong/ZS558/2015, which was detected in a live poultry market in China. This report describes the first detection of novel H5N6 reassortants in poultry during an outbreak as well as genetic characterization of these strains to better understand the antigenic evolution of influenza viruses.

Viral metagenomics analysis of poultry faeces in live poultry market, Haikou, China

Objective: To conduct in-depth study of the distribution and diversity of viruses in poultry is of great importance in monitoring the emergence of interspecies transmission of novel viruses that may cause epidemics with public health significance. Poultry is an economically important source of meat, eggs and feathers which plays an important role as natural reservoirs of many pathogenic viruses. Compared with wild animals, poultry have more frequent interactions and therefore opportunities to transmit their viruses to human. Methods: To study the viromes of different types of poultry in Hainan, China, we used metagenomics for deep viral nucleic acid sequencing of the faecal samples collected from chickens, ducks and pigeons from a live poultry market in Haikou. Result: The poultry viromes were identified by sequence similarity comparisons of viral reads (BLASTxE score, <5) against viral reference database. A total of 15 309 viral reads were obtained, approximately 13 063, 1 370 and 876 viral reads were generated from the chicken, duck, pigeon faecal samples, respectively. The majority of the sequences were homologous to the animal virus of Adenoviridae, Herpeaviridae, Picobirnaviridae, Reoviridae, Retroviridae, Circoviridae, Paramyxoviridae, Astroviridae, Caliciviridae, Coronaviridae, Picornaviridae, and Orthomyxoviridae. The VP4 and VP7 segments of a pigeon rotavirus, similar to fox rotavirus in group A, were sequenced and phylogenetically analyzed. The near full genome of a pigeon circovirus was also analyzed. Conclusion: The major types of poultry in a Haikou harbor many different families of viruses in their feces which may have the potential for interspecies transmissions. Further studies should be conducted to identify the most prevalent and important viruses among a larger number of poultry in Haikou and other areas in Hainan.

The effects of closure to live poultry markets on Avian influenza A (H7N9) epidemics in China

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 30(th) 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.

Surveillance of Live Poultry Markets for Low Pathogenic Avian Influenza Viruses in Guangxi Province, Southern China, from 2012\u20132015

Infections with low pathogenic avian influenza viruses (LPAIVs) can be mild or asymptomatic in poultry; however, in humans, LPAIVs can cause severe infections and death, as demonstrated by the H7N9 and H10N8 human infection outbreaks in 2013 in China. In this study, we conducted an epidemiological survey of LPAIVs at live poultry markets (LPMs) in Guangxi Province, Southern China, which is near several Southeast Asian countries. From January 2012 to December 2015, we collected 3,813 swab samples from poultry at LPMs in Guangxi. Viral isolation, hemagglutination inhibition assay and viral sequencing were utilized to identify LPAIVs in the collected samples. Among the samples, 622 (16.3%) were positive for LPAIVs. Six subtypes (H1, H3, H4, H6, H9 and H11) were individually isolated and identified. Of these subtypes, H3, H6 and H9 were predominant in ducks, geese and chickens, respectively. Among the 622 positive samples, 160 (25.7%) contained more than one subtype, and H8, H10, H12, H13, and H16 were identified among them, which highlights the continuous need for enhanced surveillance of AIVs. These results provide detailed information regarding the epidemic situation of LPAIVs in the area, which can aid efforts to prevent and control AIV transmission in humans and animals.

Novel Reassortant H3N2 Avian Influenza Virus Isolated from Domestic Ducks in Eastern China in 2016.

ABSTRACTH3 subtype avian influenza virus (AIV) poses a great threat to public health, and so investigating its epidemiology is of great importance. A novel reassortant H3N2 AIV strain was isolated from a live poultry market in eastern China. The strain’s genes originated from H1N1, H3, and H7 AIVs. Thus, the genome information of the H3N2 isolate will help to investigate further the epidemiology of H3 subtype AIVs in China.

Assessing the risk of downwind spread of avian influenza virus via airborne particles from an urban wholesale poultry market

Interspecies transmissions of avian influenza viruses (AIV) occur at the human-poultry interface, among which the live poultry markets (LPMs) are easily assessed by urban residents. Thousands of live poultry from different farms arrive daily at wholesale markets before being sold to retail markets. We assessed the risk of AIV downwind spread via airborne particles from a representative wholesale market in Guangzhou. Air samples were collected using the cyclone-based NIOSH bioaerosol samplers at different locations inside a wholesale market, and viral RNA and avian 18S RNA were quantified using quantitative real-time RT-PCR. Computational Fluid Dynamics (CFD) modeling was performed to investigate the AIV spread pattern. Viral RNA was readily detected from 19 out of 21 air sampling events, predominantly from particles larger than 1 μm. The concentration of viral RNA detected at the poultry holding area was 4.4 × 105 copies/m3 and was as high as 2.6 × 104 copies/m3 100 m downwind. A high concentration of avian 18S RNA (2.5 × 108 copies/m3) detected at the poultry holding area was used for assessing the potential spread of avian influenza virus during outbreak situations. CFD modeling indicated the combined effect of wind direction and surrounding buildings on the spread of virus and a slow decay rate of the virus in the air in the downwind direction. Because of the large volume of poultry trade daily, wholesale markets located in urban areas may pose considerable AIV infection risk to neighboring residents via wind spread, even in the absence of direct contact with poultry.

Airborne Transmission of Highly Pathogenic Influenza Virus during Processing of Infected Poultry.

Exposure to infected poultry is a suspected cause of avian influenza (H5N1) virus infections in humans. We detected infectious droplets and aerosols during laboratory-simulated processing of asymptomatic chickens infected with human- (clades 1 and 2.2.1) and avian- (clades 1.1, 2.2, and 2.1) origin H5N1 viruses. We detected fewer airborne infectious particles in simulated processing of infected ducks. Influenza virus–naive chickens and ferrets exposed to the air space in which virus-infected chickens were processed became infected and died, suggesting that the slaughter of infected chickens is an efficient source of airborne virus that can infect birds and mammals. We did not detect consistent infections in ducks and ferrets exposed to the air space in which virus-infected ducks were processed. Our results support the hypothesis that airborne transmission of HPAI viruses can occur among poultry and from poultry to humans during home or live-poultry market slaughter of infected poultry.

First genome report and analysis of chicken H7N9 influenza viruses with poly-basic amino acids insertion in the hemagglutinin cleavage site

We report the full-length sequence of two chicken source influenza A (H7N9) viruses found in Guangdong live poultry market (LPM) during the most recent wave of human infections (from October 2016 to the present time). These viruses carry insertion of poly-basic amino acids (KGKRTAR/G) at the protease cleavage site of the HA protein, which were previously found in the highly pathogenic (HP) human influenza A (H7N9) [IAV(H7N9)] strains. Phylogenetic analysis of these two novel avian influenza viruses (AIVs) suggested that their genomes reassorted between the Yangtze River Delta (YRD) and Pearl River Delta (PRD) clades. Molecular clock analysis indicated that they emerged several months before the HP human strains. Collectively, our results suggest that IAV(H7N9) viruses evolve in chickens through antigenic drift to include a signature HP sequence in the HA gene, which highlights challenges in risk assessment and public health management of IAV(H7N9) infections at the human-animal interface.

Identification of a novel reassortant A (H9N6) virus in live poultry markets in Poyang Lake region, China.

Live poultry markets (LPM) are one of the most important sources of human infection with avian influenza virus (AIV). During our routine surveillance of AIV, we identified an H9N6 virus (JX-H9N6) in a LPM in Nanchang city, Jiangxi Province, China. Using Bayesian coalescent analysis, it was predicted that JX-H9N6 had originated from a reassortment event between H9N2 and H6N6 AIVs in early 2014, instead of being derived from an H9N6 virus reported previously. Mutations in HA, PB1, PA, M, and NS protein, which could increase mammalian transmission and virulence, were also detected. Currently, both H9N2 and H6N6 AIVs are widely distributed in poultry and contribute to the generation of novel reassortant viruses causing human infection. Our findings highlight the importance of enhanced surveillance in birds for early prediction of human infections.

Spatial characteristics and the epidemiology of human infections with avian influenza A(H7N9) virus in five waves from 2013 to 2017 in Zhejiang Province, China.

BackgroundThe five-wave epidemic of H7N9 in China emerged in the second half of 2016. This study aimed to compare the epidemiological characteristics among the five waves, estimating the possible infected cases and inferring the extent of the possible epidemic in the areas that have not reported cases before.MethodsThe data for the H7N9 cases from Zhejiang Province between 2013 and 2017 was obtained from the China Information Network System of Disease Prevention and Control. The start date of each wave was 16 March 2013, 1 July 2013, 1 July 2014, 1 July 2015 and 1 July 2016. The F test or Pearson’s chi-square test were used to compare the characteristics of the five waves. Global and local autocorrelation analysis was carried out to identify spatial autocorrelations. Ordinary kriging interpolation was analyzed to estimate the number of human infections with H7N9 virus and to infer the extent of infections in the areas with no cases reported before.ResultThere were 45, 94, 45, 34 and 80 cases identified from the first wave to the fifth, respectively. The death rate was significantly different among the five waves of epidemics (χ2 = 10.784, P = 0.029). The age distribution (F = 0.903, P = 0.462), gender (χ2 = 2.674, P = 0.614) and occupation(χ2 = 19.764, P = 0.407) were similar in each period. Most of the cases were males and farmers. A significant trend (χ2 = 70.328, P<0.001) was identified that showed a growing proportion of rural cases. There were 31 high-high clusters and 3 high-low clusters at the county level among the five waves and 12, 8, 2, 9 and 3 clusters in each wave, respectively. The total cases infected with the H7N9 virus were far more than those that have been reported now, and the affected areas continue to expand. The epidemic in the north of Zhejiang Province persisted in all five waves. Since the second wave, the virus spread to the south areas and central areas. There was an obvious decline in the infected cases in the urban areas, and the epidemics mostly occurred in the rural areas after the fourth wave. The epidemic was relatively dispersed since the third wave had fewer than two cases in most of the areas and showed a reinforcing trend again in the fifth wave.ConclusionsThe study revealed that there were few differences in the epidemiologic characteristics among the five waves of the epidemic. However, the areas where the possible epidemic circulated was larger than reported. The epidemic cross-regional expansion continued and mostly occurred in rural areas. Continuous closure of the live poultry market (LPM) is strongly recommended in both rural and urban areas. Illegal and scattered live poultry trading, especially in rural areas, must be forbidden. It is suggested too that a more rigorous management be performed on live poultry trade and wholesale across the area. Health education, surveillance of cases and pathogenicity should also be strengthened.

Avian influenza H9N2 virus isolated from air samples in LPMs in Jiangxi, China

BackgroundRecently, avian influenza virus has caused repeated worldwide outbreaks in humans. Live Poultry Markets (LPMs) play an important role in the circulation and reassortment of novel Avian Influenza Virus (AIVs). Aerosol transmission is one of the most important pathways for influenza virus to spread among poultry, from poultry to mammals, and among mammals.MethodsIn this study, air samples were collected from LPMs in Nanchang city between April 2014 and March 2015 to investigate possible aerosol transmission of AIVs. Air samples were detected for Flu A by Real-Time Reverse Transcription-Polymerase Chain Reaction (RRT-PCR). If samples were positive for Flu A, they were inoculated into 9- to 10-day-old specific-pathogen-free embryonated eggs. If the result was positive, the whole genome of the virus was sequenced by MiSeq. Phylogenetic trees of all 8 segments were constructed using MEGA 6.05 software.ResultsTo investigate the possible aerosol transmission of AIVs, 807 air samples were collected from LPMs in Nanchang city between April 2014 and March 2015. Based on RRT-PCR results, 275 samples (34.1%) were Flu A positive, and one virus was successfully isolated with embryonated eggs. The virus shared high nucleotide homology with H9N2 AIVs from South China.ConclusionsOur study provides further evidence that the air in LPMs can be contaminated by influenza viruses and their nucleic acids, and this should be considered when choosing and evaluating disinfection strategies in LPMs, such as regular air disinfection. Aerosolized viruses such as the H9N2 virus detected in this study can increase the risk of human infection when people are exposed in LPMs.

H7N9 avian influenza A virus in China: a short report on its circulation, drug resistant mutants and novel antiviral drugs

ABSTRACTIntroduction: The first human H7N9 avian influenza virus case was reported in Shanghai in 2013. Shortly thereafter, this virus spread to other regions in China. Molecular analysis indicated that the H7N9 virus is a reassortant virus containing internal genes from the H9N2 virus and previously described mammalian adaption markers, which could allow the virus to adapt efficiently to a mammalian host. Fortunately, there is no evidence of sustained person-to-person spread. Most of the human H7N9 cases have a history of exposure to live poultry markets (LPMs). The circulating H7N9 were low pathogenic viruses, however highly pathogenic H7N9 viruses were recently identified in human cases.Areas covered: In the present article, the circulation of H7N9 in LPMs of China, the five waves of H7N9 infection in humans, recently identified drug resistant mutants and potential antiviral drugs against H7N9 are discussed; this may provide further understanding of the evolution and pandemic potential of the H7N9 influenza viruses.Expert commentary: All the data reveal that the major source of H7N9 viruses are LPMs and the H7N9 virus is still circulating widely in China. It is concerning that the recent emergence of highly pathogenic H7N9 viruses may result in highly transmissible viruses in mammalian species.

Avian influenza virus surveillance in external environment in Urumqi City during 2013 to 2015

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. Key words: Urban and rural live poultry market; External environment; Avian influenza virus

A review of global human infection with avian influenza and epidemiological characteristics

Avian influenza virus is an influenza A virus, which generally spreads among birds, without direct infection of human. According to the pathogenicity to chicken or turkey, it is divided into high, medium and low/non pathogenic. When the virus gene recombination or mutation, it will get the ability to infect human. Additionally, avian influenza virus can also infect human directly, such as H5N1, H7N9, H5N6, H10N8 subtype. The cases of human infection with avian influenza reported frequently after the outbreak of human infection with H7N7 avian influenza in 1959, the first death case due to avian influenza virus infection causing respiratory disease was the outbreak of human infection with H5N1 in Hongkong in 1997. To date, human infection with avian influenza is a global public health problem. As avian influenza viruses perpetuated in their natural hosts, with their high genetic divergence, it would be precursor viruses even for pandemic potential. In the 20th century, four influenza pandemics were closely related to avian influenza viruses, avian is the natural host of the avian influenza virus, poultry carrying virus and dead/sick poultry infected with avian influenza virus are easier to spread virus to human, the main transmission routes are birds-human transmission (exposure to sick/dead poultry) and environment-human transmission (such as visit live poultry market). Poultries exposure and chronic medical condition are the main risk factors of human infection with avian influenza. The symptoms varies including ordinary influenza-like illness (ILI), conjunctivitis, arthritis, severe pneumonia, respiratory failure , shock and death. At present, the treatment of human infection with avian influenza includes antiviral treatment, symptomatic treatment, Chinese medicine treatment, but the most important therapy of human infection with avian influenza is the treatment of antiviral drugs (neuraminidase inhibitors), using high dose antiviral drugs in the early stage can significantly improve the survival rate. PCR and real-time PCR are the best methods for preliminary diagnosis of human infection with avian influenza. At the same time, the increase of serum antibody titer in acute stage or recovery stage can alao be confirmed. In addition, effective preventive measures (such as publicity and education, behavioral intervention and vaccination development and application) are the important means to protect human from avian influenza.