**2.6 Other avian viruses in human infections: H10N8, H5N6, H7N2, H7N3, H6N1, and H10N7**

In China in 2013, human infection of avian influenza A H10N8 virus was firstly reported as severe illness which resulted in death within 9 days of clinical course [69].

**101**

avian and human isolates.

Netherlands.

*Adequate Monitor of Avian Influenza Viral Infections and Foresight About Possibilities of Its…*

This strain is different from others isolated from poultry and wild birds and reassortant of H9N2 containing genetic markers for mammalian adaptation and virulence in HA (A135T, S138A), M1 (N30D, T215A), NS1 (P42S), and PB2 (E627K). This virus

In China in 2014, human infection of avian influenza virus was caused by H5N6 HPAI virus following the epidemic infections of many birds' death [70]. Until 2017, a total of 16 human cases infected with avian influenza H5N6 and 11 fatal cases of 16 cases (an overall CFR of 69%) were reported [71]. Thirteen of 16 cases had exposure to live poultry or live poultry markets (LPMs). Avian influenza H5N6 viruses belonged to HA H5 genetic clade 2.3.4.4 have evolved from H5N1 and H9N2 viruses [72], and similar H5 clade A (H5N6) viruses have been detected in wild birds and poultry in China, Japan, Lao People's Democratic Republic, Myanmar, the Republic of Korea, and Vietnam [73]. Analyses of poultry and environmental samples indicate that the different avian influenza A H5N6 virus genotypes may

In the United States of America (USA) in 2016, avian influenza A H7N2 infected

In Canada in 2004, a two-time outbreak of avian influenza A H7N3 viral infection happened in one farm: the first was characterized as LPAI viral infection which resulted in 8–16 deaths/day among 9200 chickens in a barn, and the second was detected as HPAI viral infection which resulted in 2000 deaths in 2 days among 9030 chickens in an adjacent barn [76]. After the outbreaks of LPAI and HPAI virus infections, the examination of testing for H7N3 among approximately 2000 poultry farm workers and 650 workers assisted with outbreak management and control revealed 57 suspected and/or confirmed as avian influenza infections [76]. Only two confirmed patients with avian influenza A H7N3 virus had conjunctivitis and mild influenza-like illness cases infected with avian influenza A H7N7 virus in the

In Taiwan in 2013, a human infection with avian influenza A H6N1 was recognized as mild pneumonia and quick improvement by treated oseltamivir. A 20-year-old woman works at a breakfast shop and had not been exposed to poultry or birds and no travel to China. Investigation of 36 close contacts with her cleared no positive tests for avian influenza A H6N1, and two poultry farms within 1 km from the woman's house were investigated as the results of no H6N1 virus infection [77]. Avian influenza A H6N1 virus strain commonly circulates in domestic birds in Taiwan, and this infection happened to be found in the alert of a Taiwanese traveler's infection with epidemic avian influenza H7N9 virus in China in 2013. Genetic and structural analysis of isolated H6N1 virus reveals that a single nucleotide substitution resulting in a change from Gly to Asp at position 225 of HA (G225D) leads to direct interaction of Asp225 with the penultimate of Gal of the human-type receptor and the stabilized binding to human receptor [78]. E627K mutation in PB2 is well known to human adaptation of avian influenza viruses but is not present in

one human after an outbreak of infection among cats in an animal shelter in New York City. This person's infection was associated with close contact with sick cats affected with H7N2-isolated virus and no widespread to any other persons [74]. Avian influenza H7N2 viral infection to humans has been reported as the result of prolonged long contact with infected birds since 2002 in the USA. But the screening of more than 350 people with exposure to infected cats during this outbreak appeared no more human infection except one, and the risk posed by this virus to the public was thought to be low. Isolated H7N2 viruses in the USA are characterized as LPAI virus but have increased binding to sialic acid-α2,6-galactose receptor and reduced binding to sialic acid-α2,3-galactose receptor which has the possibility of

*DOI: http://dx.doi.org/10.5772/intechopen.86551*

human-to-human infection [75].

was sensitive to neuraminidase inhibitors (NAIs) [69].

vary by geographic regions as HPAI viruses or LPAI viruses [73].

*Adequate Monitor of Avian Influenza Viral Infections and Foresight About Possibilities of Its… DOI: http://dx.doi.org/10.5772/intechopen.86551*

This strain is different from others isolated from poultry and wild birds and reassortant of H9N2 containing genetic markers for mammalian adaptation and virulence in HA (A135T, S138A), M1 (N30D, T215A), NS1 (P42S), and PB2 (E627K). This virus was sensitive to neuraminidase inhibitors (NAIs) [69].

In China in 2014, human infection of avian influenza virus was caused by H5N6 HPAI virus following the epidemic infections of many birds' death [70]. Until 2017, a total of 16 human cases infected with avian influenza H5N6 and 11 fatal cases of 16 cases (an overall CFR of 69%) were reported [71]. Thirteen of 16 cases had exposure to live poultry or live poultry markets (LPMs). Avian influenza H5N6 viruses belonged to HA H5 genetic clade 2.3.4.4 have evolved from H5N1 and H9N2 viruses [72], and similar H5 clade A (H5N6) viruses have been detected in wild birds and poultry in China, Japan, Lao People's Democratic Republic, Myanmar, the Republic of Korea, and Vietnam [73]. Analyses of poultry and environmental samples indicate that the different avian influenza A H5N6 virus genotypes may vary by geographic regions as HPAI viruses or LPAI viruses [73].

In the United States of America (USA) in 2016, avian influenza A H7N2 infected one human after an outbreak of infection among cats in an animal shelter in New York City. This person's infection was associated with close contact with sick cats affected with H7N2-isolated virus and no widespread to any other persons [74]. Avian influenza H7N2 viral infection to humans has been reported as the result of prolonged long contact with infected birds since 2002 in the USA. But the screening of more than 350 people with exposure to infected cats during this outbreak appeared no more human infection except one, and the risk posed by this virus to the public was thought to be low. Isolated H7N2 viruses in the USA are characterized as LPAI virus but have increased binding to sialic acid-α2,6-galactose receptor and reduced binding to sialic acid-α2,3-galactose receptor which has the possibility of human-to-human infection [75].

In Canada in 2004, a two-time outbreak of avian influenza A H7N3 viral infection happened in one farm: the first was characterized as LPAI viral infection which resulted in 8–16 deaths/day among 9200 chickens in a barn, and the second was detected as HPAI viral infection which resulted in 2000 deaths in 2 days among 9030 chickens in an adjacent barn [76]. After the outbreaks of LPAI and HPAI virus infections, the examination of testing for H7N3 among approximately 2000 poultry farm workers and 650 workers assisted with outbreak management and control revealed 57 suspected and/or confirmed as avian influenza infections [76]. Only two confirmed patients with avian influenza A H7N3 virus had conjunctivitis and mild influenza-like illness cases infected with avian influenza A H7N7 virus in the Netherlands.

In Taiwan in 2013, a human infection with avian influenza A H6N1 was recognized as mild pneumonia and quick improvement by treated oseltamivir. A 20-year-old woman works at a breakfast shop and had not been exposed to poultry or birds and no travel to China. Investigation of 36 close contacts with her cleared no positive tests for avian influenza A H6N1, and two poultry farms within 1 km from the woman's house were investigated as the results of no H6N1 virus infection [77]. Avian influenza A H6N1 virus strain commonly circulates in domestic birds in Taiwan, and this infection happened to be found in the alert of a Taiwanese traveler's infection with epidemic avian influenza H7N9 virus in China in 2013. Genetic and structural analysis of isolated H6N1 virus reveals that a single nucleotide substitution resulting in a change from Gly to Asp at position 225 of HA (G225D) leads to direct interaction of Asp225 with the penultimate of Gal of the human-type receptor and the stabilized binding to human receptor [78]. E627K mutation in PB2 is well known to human adaptation of avian influenza viruses but is not present in avian and human isolates.

*Viruses and Viral Infections in Developing Countries*

respiratory tract [61].

**2.5 Avian influenza A H9N2 viruses**

appearance of H7N9 and H10N8 [68, 69].

**H6N1, and H10N7**

were applied to HPAI virus infection in poultry leading to the potential start of human influenza pandemic, such as culling and banning the movement of infected flocks and tracing and screening of the infection which were implemented, followed by preemptive culling of flocks in a 1-km zone around the infected flock. In this HPAI viral epidemic in poultry, 86 poultry workers and 3 household contacts were identified to be affected with H7N7 by RT-PCR, and the main symptom of this infection was conjunctivitis (83/89 persons) and one fatal case happened [60, 61]. Since 2006–2011 LPAI virus infection in the Netherlands (2006) and in Germany (2011) and HPAI virus infection in England (2008) and in Spain (2009), H7N7 viral infections were reported. These show the difficulty in the elimination of epidemic avian influenza viral infection from the endemic avian influenza virus infection among wild waterfowls. As additional measures, vaccination for poultry in outbreaks of H7N7 significantly reduced the excretion of viruses, which may reduce virus spread in infected areas and the risk of human exposure to viruses, in Italy (2000) [62]. Compared with the H7N1 and H7N3 episodes leading no bird to human transmission in Italy, in the genetic analysis of H7N7, HA gene of H7N7 is quite similar to HA genes of H7N1 and H7N3. So other mutations in NA or internal genes of H7N7 virus including E627K in PB2 except HA may determine the capacity to replicate and cause disease in humans. Although H7N7 virus may replicate well in the human cells near the eyes, it may not well replicate in the human upper

Influenza virus A H9N2 has been firstly known in 1966 as the infection among turkeys in Wisconsin. Until 1998–1999, influenza H9N2 viruses are less considered to be as zoonotic transmission, although this H9N2 widespread is nearly global including several Asian countries among from wild birds to domestic poultry populations [63]. H9N2 viruses are characterized as LPAI viruses that have caused mild disease which led to decreased egg production and deaths in poultry [64]. In China, natural human infections with H9N2 were firstly reported as seropositive cases in Guangdong province in 1998 and several cases with mild or asymptomatic illness in the South or mainland China and Hong Kong in 1999 [65]. H9N2 LPAI viruses, that were isolated from an infected human in Pakistan in 2012–2015 and in Northern China in 2017, have an identical amino acid residue leucine at 226 in the receptor binding site of HA, the C-terminus of PDZ ligand motif in NS1 (KSEI), NP (E372D), and L55F in the M2 protein that are mammalian host-specific markers [64, 66]. Avian influenza H9N2 viral infections have been globally distributed as mild and asymptomatic infection in humans, poultry, pet birds, and other domestic animals and may trigger weak immune responses and production of low titer of antibody to H9N2 in humans [63, 66]. These were inducted as infections from poultry to humans directly or indirectly, but not as human-to-human transmission [63, 66]. Low rates of influenza A H9N2 viral infection in poultry-exposed individuals may cause an epidemic with a longer duration or a greater magnitude than if the virus was introduced to a completely unexposed population [67]. H9N2 also demonstrates its potential to efficient transmission from avian hosts and sharing genetic materials (e.g., internal genes) with other viruses as

**2.6 Other avian viruses in human infections: H10N8, H5N6, H7N2, H7N3,** 

In China in 2013, human infection of avian influenza A H10N8 virus was firstly reported as severe illness which resulted in death within 9 days of clinical course [69].

**100**

In Australia in 2010, an outbreak of LPAI H10N7 viruses was identified as 10–25 bird's deaths for 8–14 days, a 15% decrease of egg production, and no respiratory signs in affected flocks. Two of seven abattoirs who had conjunctivitis and minor upper respiratory tract symptoms were identified to be infected by H10N7 virus [79]. In Australia in 2010, surveillance for H10N7 viruses showed small numbers of wild waterfowl on the affected site and no infection of H10 subtypes in poultry around 2 km of affected farms.

#### **2.7 Other strains of avian influenza viruses.**

In addition to avian influenza strains of poultry to human infections, epidemics of avian influenza A strains are reported: H5N2, H5N5, and H5N8 viruses as HPAI viruses and H3N8, H6N6, H10N4, H10N5, H11N2, and H7N8 as occasional infection to mammals.
