Dataset Information

Surveillance of Avian H7N9 Virus in Various Environments of Zhejiang Province, China before and after Live Poultry Markets Were Closed in 2013-2014.

ABSTRACT:

Background

To date, there have been a total of 637 laboratory-confirmed cases of human infection with avian influenza A (H7N9) virus across mainland China, with 28% (179/637) of these reported in Zhejiang Province. Surveillance of avian H7N9 virus was conducted to investigate environmental contamination during H7N9 outbreaks. We sought to evaluate the prevalence of H7N9 in the environment, and the effects of poultry market closures on the incidence of human H7N9 cases.

Methods

We collected 6740 environmental samples from 751 sampling sites across 11 cities of Zhejiang Province (China) between January 2013 and March 2014. The presence of H7N9 was determined by reverse transcription polymerase chain reaction, with prevalence compared between sites and over time. The relationship between environmental contamination and human cases of H7N9 infection were analyzed using Spearman's ranked correlation coefficient.

Results

Of the 6740 samples, 10.09% (680/6740) were H7N9-positive. The virus was found to circulate seasonally, and peaked during the spring and winter of 2013-2014. The prevalence of the virus decreased from the north to the southeast of the province, coinciding with the geographical distribution of human H7N9 cases. Compared with other sampling sites, live poultry markets (LPMs) had the highest prevalence of H7N9 virus at 13.94% (667/4784). Of the various sample types analyzed, virus prevalence was highest for chopping board swabs at 15.49% (110/710). The prevalence of the virus in the environment positively correlated with the incidence of human H7N9 cases (r2 = 0.498; P < 0.01). Cities with a higher incidence of human H7N9 cases also had a higher prevalence of H7N9 among samples and at sampling sites. Following the closure of LPMs at the end of January 2014, the prevalence of H7N9 decreased from 19.18% (487/2539) to 6.92% (79/1141). This corresponded with a decrease in the number of human H7N9 cases reported.

Conclusions

The prevalence of H7N9 virus in environmental samples oscillated seasonally, regardless of whether LPMs were open. The presence of H7N9 in environmental samples positively correlated with the number of human H7N9 cases, indicating that eradication of the virus from the environment is essential in reducing the numbers of H7N9 cases and halting the spread of the virus.

SUBMITTER: Wang X

PROVIDER: S-EPMC4550274 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Publications

Surveillance of Avian H7N9 Virus in Various Environments of Zhejiang Province, China before and after Live Poultry Markets Were Closed in 2013-2014.

Wang Xiaoxiao X Liu Shelan S Mao Haiyan H Yu Zhao Z Chen Enfu E Chai Chengliang C

PloS one 20150826 8

<h4>Background</h4>To date, there have been a total of 637 laboratory-confirmed cases of human infection with avian influenza A (H7N9) virus across mainland China, with 28% (179/637) of these reported in Zhejiang Province. Surveillance of avian H7N9 virus was conducted to investigate environmental contamination during H7N9 outbreaks. We sought to evaluate the prevalence of H7N9 in the environment, and the effects of poultry market closures on the incidence of human H7N9 cases.<h4>Methods</h4>We ...[more]

PMID: 26308215

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Project description:Background and aimsH9N2 subtype avian influenza virus (AIV) has low-pathogenicity but causes respiratory symptoms and drop in egg production in chicken with long-term virus shedding, resulting in great economic losses due to high mortality related to secondary infection with other pathogens. In recent years, H9N2 viruses have been posing a threat to public health, causing human infection in China. Compared to studies on other AIV subtypes, there are relatively few studies on the pathogenic mechanism of the H9N2 virus in mammals. H9N2 subtype AIV has been circulating worldwide in many avian species and transmitting with high efficiency in poultry. It can provide internal genes for other subtypes to produce new viruses, causing a pandemic risk. It is important to carry out long-term surveillance and pathogenic characteristics of the H9N2 virus. In this study, we conducted environmental surveillance of live poultry markets in Anhui province from 2013 to 2018, and 33 representative environmental isolates were selected and studied systematically.MethodsThe genomic RNA of Anhui H9N2 isolates was subjected to RT-PCR amplification followed by sequencing analysis.ResultsThirty-three strains were isolated from the embryonated eggs of specific-pathogen-free chickens. Phylogenetic analysis indicated that h9.4.2.5-like H9N2 viruses were predominant during 2013-2018 and acquired multiple specific amino acid mutations that may have increased their affinity for mammals and enhanced their infectivity and transmissibility. Additionally, six internal genes of H9N2 clustered together with the novel human-lethal reassortant viruses, such as the low-pathogenicity H7N9, H10N8, and Anhui H5N6 viruses, and even HPAI H7N9.ConclusionBecause H9N2 viruses may be the donors of internal genes that lead to the generation of novel reassortant viruses with enhanced pathogenicity in Anhui province, continuous environmental surveillance of live poultry markets, a key source of reassorted H9N2 and other avian influenza viruses, is of great importance.

Project description:BackgroundHuman infection of avian influenza virus (AIV) remains a great concern. Although live poultry markets are believed to be associated with human infections, ever more infections have been reported in rural areas with backyard poultry, especially in the fifth epidemic of H7N9. However, limited information is available on backyard poultry infection and surrounding environmental contamination.MethodsTwo surveillance systems and a field survey were used to collect data and samples in Zhejiang Province. In total, 4538 samples were collected by surveillance systems and 3171 from the field survey between May 2015 and May 2017, while 352 backyard poultry owners were interviewed in May 2017 by questionnaire to investigate factors influencing the prevalence of avian influenza A virus and other AIV subtypes. RT-PCR was used to test the nucleic acids of viruses. ArcGIS 10.1 software was used to generate maps. Univariate and logistic regression analyses were conducted to identify risk factors for AIV infection.ResultsOf the 428 poultry premises observed by the surveillance system, 53 (12.38%) were positive for influenza A virus. Of the 352 samples from poultry premises observed by field survey, 13 (3.39%) were positive for influenza A virus. The prevalence of AIV was unevenly distributed and the dominant subtype differed among cities. Eastern (Shaoxing and Ningbo) and southern (Wenzhou) cities exhibited a higher prevalence of AIV (16.33, 8.94, and 7.30% respectively). Contamination of AIV subtypes was most severe in January, especially in 2016 (23.26%, 70/301). The positive rate of subtype H5/H7/H9 was 2.53% (115/4538). Subtype H5 was the least prevalent, while subtypes H7 and H9 had similar positivity rates (1.50 and 1.32% respectively). Poultry flocks and environmental samples had a similar prevalence of AIV (4.46% vs 5.06%). The type of live birds was a risk factor and the sanitary condition of the setting was a protective factor against influenza A contamination.ConclusionsAIV subtypes were prevalent in backyard poultry flocks and surrounding environments in Zhejiang Province. The types of live birds and sanitary conditions of the environment were associated with influenza A contamination. These findings shine a light on the characteristics of contamination of AIV subtypes and emphasize the importance of reducing AIV circulation in backyard poultry settings.

Dataset Information

Surveillance of Avian H7N9 Virus in Various Environments of Zhejiang Province, China before and after Live Poultry Markets Were Closed in 2013-2014.

Background

Methods

Results

Conclusions

Publications

Surveillance of Avian H7N9 Virus in Various Environments of Zhejiang Province, China before and after Live Poultry Markets Were Closed in 2013-2014.

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