Public health risk upon human exposure to highly pathogenic avian influenza H5N8

Baars, I. (2017) Public health risk upon human exposure to highly pathogenic avian influenza H5N8. Master's Thesis / Essay, Biomedical Sciences.

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Abstract

Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: the hemagglutinin (HA) and the neuraminidase (NA). Influenza A viruses mainly affect avian species, but some highly pathogenic avian Influenza (HPAI) A subtypes can undergo reassortment or can acquire mutations, which can result in a novel virus strain capable of mammalian or even human infection. A recent outbreak of HPAI H5N8 in Korea has been reported with no human cases to date. However, other HPAI H5 viruses have been associated with human infection. Therefore, the potential public health risk upon human exposure to HPAI H5N8 was assessed in this review. The novel reassortant HPAI H5N8 is subdivided into group A and group B viruses based on genetic differences. Group A viruses were predominant during the initial outbreak, but group B viruses were predominant during a new outbreak in 2016, suggesting these viruses are the main threat to human health to date. The introduction of H5N8 viruses into Korea and the spread of H5N8 viruses to Europe, Russia and North America has been attributed to migration of wild birds, suggesting rapid geographical spread of HPAI H5N8 viruses and limited surveillance. H5N8 viruses were able to affect both avian species and mammalian species and pathogenicity was considered mild in both avian and mammalian species. However, while horizontal transmission in avian species was efficient, horizontal transmission in mammalian species was unsuccessful. HPAI H5N8 viruses preferentially bound avian-like receptors and showed insufficient replication in human cells, indicating that HPAI H5N8 are not fully adapted to mammals. Findings suggested a difference between group A and group B viruses, with group B viruses being more pathogenetic and more adapted to humans than group A viruses. Additionally, currently circulating HPAI H5N8 viruses were shown to be susceptible to NAIs and certain vaccines were shown to protect against H5N8 infection. However, susceptibility to treatment can be altered when mutations occur. These results together suggest that the public health risk of the HPAI H5N8 strains is low. However, the rapid geographical spread of HPAI H5N8 viruses, their ability to infect various avian and mammalian species without causing clinical signs and the tendency of influenza A viruses to mutate and reassort are major concerns. Therefore, it seems of interest to extensively monitor the spread of HPAIVs, especially in areas where migratory bird species congregate.

Item Type:	Thesis (Master's Thesis / Essay)
Degree programme:	Biomedical Sciences
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Feb 2018 08:32
Last Modified:	15 Feb 2018 08:32
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/16042

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