Natural history of highly pathogenic avian influenza H5N1

Abstract

The ecology of highly pathogenic avian influenza (HPAI) H5N1 has significantly changed from sporadic outbreaks in terrestrial poultry to persistent circulation in terrestrial and aquatic poultry and potentially in wild waterfowl. A novel genotype of HPAI H5N1 arose in 1996 in southern China and through ongoing mutation, reassortment, and natural selection, has diverged into distinct lineages and expanded into multiple reservoir hosts. The evolution of Goose/Guangdong-lineage highly pathogenic H5N1 viruses is ongoing: while stable interactions exist with some reservoir hosts, these viruses are continuing to evolve and adapt to others, and pose an un-calculable risk to sporadic hosts, including humans.

Emergence of a novel cluster of influenza A(H5N1) virus clade 2.2.1.2 with putative human health impact in Egypt, 2014/15

“…Since their emergence in Asia in 2003, HPAI viruses of subtype H5N1 and their recent descendants continue to cause significant economic losses to commercial poultry not only in Asia, but also in Egypt where high mortality in poultry has continuously been observed since 2006 [11,12]. They also exhibit strain-specific zoonotic potential resulting in sporadic avian-to-human spillover transmissions which lead to human infections associated with a high case fatality rate [13]. However, apart from sporadic cases (e.g., family clusters) sustained human-to-human transmission of any of these viruses has not ensued so far.…”

Analysis of signs and pathology of H5N1-infected ducks from the 2010–2011 Korean highly pathogenic avian influenza outbreak suggests the influence of age and management practices on severity of disease

“…Influenza virus, a segmented negative-sense RNA virus, is a member of the Orthomyxoviridae family that includes the genera influenza virus A, B and C. Among the three influenza virus types, the influenza type A virus is known to infect several avian and mammalian species (Webster et al, 1992;Sonnberg et al, 2013). The influenza type A virus genome consists of eight segments of linear negative-sense, singlestranded RNA that encode 11 viral proteins including the envelope glycoprotein, haemagglutinin (HA), which plays an important role in host invasion (Neumann et al, 2007).…”

Histopathological findings in Dalmatian pelicans (Pelecanus crispus) naturally infected with avian influenza subtype A H5N1 in Bulgaria

“…Data about the predecessor of this virus causing the death of a large numbers of geese was collected in 1996 in China (Tang et al, 1998). Since then, for 18 years until 2014, H5N1 has undergone significant evolution and has generated many different clades due to antigenic drift in the H5 gene (Sonnberg et al, 2013). On the 25 th of March 2015, the H5N1 was confirmed (after VI and RT-PCR) to be the cause of death of 21 dalmatian pelicans in Srebarna reserve.…”