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Surveillance of avian influenza viruses from 2009 to 2013 in South Korea.

ABSTRACT: Avian influenza viruses (AIVs) are carried by wild migratory waterfowl across migratory flyways. To determine the strains of circulating AIVs that may pose a risk to poultry and humans, regular surveillance studies must be performed. Here, we report the surveillance of circulating AIVs in South Korea during the winter seasons of 2009-2013. A total of 126 AIVs were isolated from 7942 fecal samples from wild migratory birds, with a total isolation rate of 1.59%. H1‒H7 and H9‒H11 hemagglutinin (HA) subtypes, and N1‒N3, N5, and N7‒N9 neuraminidase (NA) subtypes were successfully isolated, with H6 and N2 as the most predominant HA and NA subtypes, respectively. Sequence identity search showed that the HA and NA genes of the isolates were highly similar to those of low-pathogenicity influenza strains from the East Asian-Australasian flyway. No match was found for the HA genes of high-pathogenicity influenza strains. Thus, the AIV strains circulating in wild migratory birds from 2009 to 2013 in South Korea likely had low pathogenicity. Continuous surveillance studies such as this one must be performed to identify potential precursors of influenza viruses that may threaten animal and human health.

SUBMITTER: Nam JH

PROVIDER: S-EPMC8671502 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundNational surveillance of avian influenza virus (AIV) in South Korea has been annually conducted for the early detection of AIV and responses to the introduction of highly pathogenic avian influenza (HPAI) virus. In this study, we report on a nationwide surveillance study of AIV in domestic poultry and wild birds in South Korea between 2012 and 2014.MethodsDuring the surveillance programs between 2012 and 2014, 141,560 samples were collected. Of these, 102,199 were from poultry farms, 8215 were from LBMs, and 31,146 were from wild bird habitats. The virus isolation was performed by inoculation of embryonated chicken eggs and AIV isolates were detected using hemagglutination assay. For subtying of AIV, the hemagglutinin and neuraminidase genes were confirmed by sequencing. Phylogenetic analysis of the H5 subtypes was performed using 28 H5 AIV isolates.ResultsBetween 2012 and 2014, a total of 819 AIV were isolated from 141,560 samples. Virus isolation rates for AIV were 0.6, 0.4, 0.1, and 2.7% in wild birds (n = 202), domestic ducks (n = 387), minor poultry (n = 11), and the live bird market (LBM) (n = 219), respectively. In wild birds, various subtypes were found including H1-H7 and H9-H13. The major subtypes were H5 (n = 48, 23.9%: N3 (n = 4) and N8 (n = 44)), H4 (n = 39, 19.4%), and H1 (n = 29, 14.4%). In domestic poultry, mainly ducks, the H5N8 (n = 275, 59.3%), H3 (n = 30, 17.2%), and H6 (n = 53, 11.4%) subtypes were predominantly found. The most frequently detected subtypes in LBM, primarily Korean native chicken, were H9 (n = 169, 77.2%). H3 (n = 10, 4%) and H6 (n = 30, 13.7%) were also isolated in LBM. Overall, the prevalence of AIV was found to be higher between winter and spring and in western parts of South Korea. The unusual high prevalence of the H5 subtype of AIV was due to the large scale outbreak of H5N8 HPAI in wild birds and domestic poultry in 2014.ConclusionsEnhanced surveillance and application of effective control measures in wild birds and domestic poultry, including LBM, should be implemented to control AI and eradicate HPAI.

Project description:INTRODUCTION: More than 70 outbreaks of the highly pathogenic avian influenza (HPAI) H5N1 have been reported in poultry in the western and north-eastern parts of India. Therefore, in view of the recent HPAI H5N1 outbreaks in poultry, active AI surveillance encompassing wild, resident, migratory birds and poultry was undertaken during 2009-2011 in the State of West Bengal. METHODS: A total of 5722 samples were collected from West Bengal; 3522 samples (2906 fecal droppings?+?616 other environmental samples) were from migratory birds and 2200 samples [1604 tracheal, cloacal swabs, environmental samples, tissue samples?+?596 blood (serum)] were from domestic ducks and poultry. All tracheal, cloacal and environmental samples were processed for virus isolation. Virus isolates were detected using hemagglutination assay and identified using hemagglutination inhibition (HI) and reverse transcriptase polymerase chain reaction (RT-PCR) assays. Sequencing and phylogenetic analysis of partial region of the hemagglutinin and neuraminidase genes was done. Intravenous pathogenicity index assays were performed in chickens to assess pathogenicity of AI virus isolates. Serum samples were tested for detection of antibodies against AI viruses using HI assay. RESULTS: A total of 57 AI H9N2, 15 AI H4N6 and 15 Newcastle Disease (NDV) viruses were isolated from chickens, from both backyard and wet poultry markets; AI H4N6 viruses were isolated from backyard chickens and domestic ducks. Characterization of AI H9N2 and H4N6 viruses revealed that they were of low pathogenicity. Domestic ducks were positive for antibodies against H5 and H7 viruses while chickens were positive for presence of antibodies against AI H9N2 and NDV. CONCLUSIONS: In the current scenario of HPAI H5N1 outbreaks in West Bengal, this report shows presence of low pathogenic AI H9N2 and H4N6 viruses in chickens and domestic ducks during the period 2009-2011. This is the first report of isolation of H4N6 from India. Antibodies against AI H5 and H7 in ducks highlight the probable role of domestic ducks in the transmission of AI viruses. Human infections of H9N2 have been reported from China and Hong Kong. This necessitates implementation of prevention and control measures to limit the spread of AI viruses.

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Surveillance of avian influenza viruses from 2009 to 2013 in South Korea.

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