Serological and virological surveillance of avian influenza virus in domestic ducks of the north-east region of Bangladesh

Rahul Deb Sarker,Emdadul Haque Chowdhury,Mohammad Giasuddin,Mohammad Rafiqul Islam

doi:10.1186/s12917-017-1104-6

Rahul Deb Sarker, Emdadul Haque Chowdhury + Show 2 more

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https://doi.org/10.1186/s12917-017-1104-6

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Abstract

BackgroundWild waterfowl are considered as the natural reservoir for avian influenza (AI) viruses. Bangladesh has been experiencing highly pathogenic avian influenza (HPAI) outbreaks since 2007, mostly in chickens and occasionally in ducks. Ducks play an important role in the persistence and genetic recombination of AI viruses. This paper presents the results of serological and virological monitoring of AI in domestic ducks in 2013 in the north-east region of Bangladesh.ResultsA total of 871 and 662 serum samples and 909 and 302 pairs of cloacal and oropharyngeal swabs from domestic ducks of Mymensingh and Sylhet division, respectively, were analysed. Antibodies to type A influenza virus were detected by blocking ELISA in 60.73 and 47.73% serum samples of Mymensingh and Sylhet division, respectively. On haemagglutination-inhibition (HI) test 17.5% of ELISA positive serum samples were found to be seropositive to H5 avian influenza virus. Five cloacal swabs and one oropharyngeal swab were positive for M gene of type A influenza virus by real time RT-PCR (rRT-PCR), but all of them were negative for H5 influenza virus. Three of the six viruses were successfully characterized as H1N5, H2N5 and H7N5 subtype of AI virus, the other three remained uncharacterized. On sequencing and phylogenetic analysis the HA and NA genes were found to be of Eurasian avian lineage. The H7 virus had cleavage site motif of low pathogenic virus.ConclusionsLow pathogenic avian influenza viruses were detected from apparently healthy domestic ducks. A small proportion of domestic ducks were found seropositive to H5 AI virus.

Highlights

Wild waterfowl are considered as the natural reservoir for avian influenza (AI) viruses
Influenza viruses in birds are classified as either low pathogenic avian influenza (LPAI) or highly pathogenic avian influenza (HPAI)
Serosurveillance A total of 871 and 662 serum samples out of 909 and 671 samples collected from Mymensingh and Sylhet division, respectively, were tested by Enzyme-linked immunosorbent assay (ELISA) for antibodies to type A influenza viruses

Summary

Introduction

Wild waterfowl are considered as the natural reservoir for avian influenza (AI) viruses. Bangladesh has been experiencing highly pathogenic avian influenza (HPAI) outbreaks since 2007, mostly in chickens and occasionally in ducks. Ducks play an important role in the persistence and genetic recombination of AI viruses. Wild waterfowl serve as the natural reservoir for Type A influenza viruses and play an important role in the persistence and transmission of these viruses among birds and other mammalian species. Influenza viruses in birds are classified as either low pathogenic avian influenza (LPAI) or highly pathogenic avian influenza (HPAI). In addition to H5N1 HPAI, low pathogenic H9N2 influenza virus has been circulating in poultry [14,15,16]

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