Abstract
Highly pathogenic avian influenza H5N1 viruses were first isolated in Bangladesh in February 2007. Subsequently, clades 2.2.2, 2.3.4.2 and 2.3.2.1a were identified in Bangladesh, and our previous surveillance data revealed that by the end of 2014, the circulating viruses exclusively comprised clade 2.3.2.1a. We recently determined the status of circulating avian influenza viruses in Bangladesh by conducting surveillance of live poultry markets and waterfowl in wetland areas from February 2015 through February 2016. Until April 2015, clade 2.3.2.1a persisted without any change in genotype. However, in June 2015, we identified a new genotype of H5N1 viruses, clade 2.3.2.1a, which quickly became predominant. These newly emerged H5N1 viruses contained the hemagglutinin, neuraminidase and matrix genes of circulating 2.3.2.1a Bangladeshi H5N1 viruses and five other genes of low pathogenic Eurasian-lineage avian influenza A viruses. Some of these internal genes were closely related to those of low pathogenic viruses isolated from ducks in free-range farms and wild birds in a wetland region of northeastern Bangladesh, where commercially raised domestic ducks have frequent contact with migratory birds. These findings indicate that migratory birds of the Central Asian flyway and domestic ducks in the free-range farms in Tanguar haor-like wetlands played an important role in the emergence of this novel genotype of highly pathogenic H5N1 viruses.Emerging Microbes & Infections (2017) 6, e72; doi:10.1038/emi.2017.60; published online 9 August 2017
Highlights
Pathogenic avian influenza (HPAI) H5N1 viruses emerged as a human pathogen in 1997 in Hong Kong.[1]
All of the viruses were isolated from ducks except for a single H7N5 virus (A/black-tailed godwit/Bangladesh/24734/2015), which was isolated from a fecal sample of a migratory black-tailed godwit
Ducks raised in free-range duck farms in wetland areas have considerable contact with wild migratory birds in production sites, and with other poultry animals in live poultry markets (LPMs)
Summary
Pathogenic avian influenza (HPAI) H5N1 viruses emerged as a human pathogen in 1997 in Hong Kong.[1] Since that outbreak, H5N1 viruses spread out of East Asia, across Eurasia, and as far as England and West Africa. The viruses are of great concern for public health. Since the reemergence of H5N1 viruses in 2003, 856 laboratory-confirmed cases of human infection, including at least 452 deaths, were reported to the World Health Organization.[2]. The first HPAI H5N1 virus detected, A/Goose/Guangdong/1/1996 (H5N1), was identified in 1996 in Guangdong, China and is considered the progenitor H5N1 virus from which present panzootic H5N1 viruses have evolved.[3] contemporary H5N1 viruses contain only the hemagglutinin (HA) gene derived from the progenitor H5N1 virus. The remaining seven viral genes were acquired by genetic reassortment with other avian influenza viruses.[4] For the past
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have