Rokshana Parvin
Department of Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Mohammed Nooruzzaman
Department of Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Congriev Kumar Kabiraj
Department of Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Jahan Ara Begum
Department of Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Emdadul Haque Chowdhury
Department of Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Mohammad Rafiqul Islam
Department of Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
Timm Harder
National Reference Laboratory for Avian Influenza (NRL-AI), Institute of Diagnostic Virology, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Suedufer 10, 17493 Greifswald-Insel Riems, Germany
Bangladesh, Poultry, Live bird market, Avian influenza virus, Genotype, Pathotype, Control
Risk Management in Agriculture
Poultry, Virus
Geographical and Ecological Frameworks: Bangladesh is a low to a middle-income country in South Asia agriculturally characterized by rich water environments, paddy rice farming, and poultry production. The economy is heavily dependent on agriculture and livestock production. The country consists of a broad, deltaic plain with many tributaries and a sea coast with an extensive mangrove belt. It is at high risk of frequent flooding by three major rivers, the Ganges, Jamuna, and the Brahmaputra. In addition, there is annual flooding from the seaside due to cyclones in the Bengal Bay of the Indian Ocean. Bangladesh is also an attractive and important wintering site for wild migratory birds, in particular, of the order Anseriformes, which breed in arctic and palearctic regions of Russia. Moreover, two major migratory bird flyways, the Central Asian and East Asian-Australian, are crossing Bangladesh. The abundance of shallow coastal wetlands and vast inland wetlands (so-called haors) provide a large reservoir for wildlife, especially waterfowl, which migrate from many parts of Russia and Central Asia during winter. This creates an ecological scenario where wild aquatic birds, domestic ducks and galliform poultry intermingle and in which pathogens, like AIV, can be easily exchanged. Poultry Rearing Systems and Trading Chains: Poultry rearing in Bangladesh comprises commercial and backyard poultry production.Commercial farming can be further categorized according to farm sizes following the sectoring approach of the Food and Agriculture Organization of the United States (FAO) [38]: large-scale breeder farming, medium size farming (broiler, layer, and duck), and small size farming (layer, broiler, quail, pigeon, turkey, guinea fowl, etc.). In Bangladesh, more than 60% of the people live in rural villages, and it is estimated that about 90% of the rural households raise poultry (chicken, duck, pigeon) in traditional backyard settings. Virus Transmission and Risk Factors: Droplet, aerosol, faeco-oral, and direct or indirect contact with contaminated materials are widely described modes of transmission of AIVs [54]. Transmission risks increase depending on host susceptibility and viral load in the environment, as well as on distance between and frequency of contacts. In Bangladesh, the domestic duck is currently considered as the most important epidemiological factor associated with AIV transmission between wild birds and other poultry. Overview of AIV Sub- and Pathotypes in Bangladesh: Viral nucleotide sequences of AIVs detected in Bangladesh were retrieved from public sequence databases (GenBank at National Center for Biotechnology Information (NCBI) or EpiFlu of the Global Initiative on Sharing Avian Influenza Data (GISAID) or Influenza Research Database (IRD)). Until December 2019, a total of 582 fully sequenced avian origin AIV isolates were available. About 79% of these were obtained from domestic birds (n = 462 HA, 461 NA), 14% from environmental samples (n = 84 HA, 83 NA) and 6% from wild birds (n = 36 HA, 35 NA), Supplemental. Although a wide variation of different subtypes was described, HPAIV H5N1 and LPAIV H9N2 constitute the dominant circulating subtypes in poultry and are endemic in the country. HPAI Virases: In the 21st century, HPAI viruses eventfully affected domestic poultry with significant public health and economic concerns throughout South East Asia. In particular, the H5N1 HPAI viruses of the gs/GD lineage, soon after its emergence in Guangdong, China, have become endemically established in domestic poultry across Asia and Africa or have caused excessive epidemics throughout Europe and in North America.
Review Paper: Department of Pathology, Faculty of Veterinary Science, BAU, Mymensingh, 26 June 2020
Journal