Influenza viruses

Figures & data

Table 1. Reported cases of avian influenza virus infection determined by viral isolation

Host of origin		Year, Place	Patho-type	Virus subtype	Associated activity	Ref.
Wild birds	Swans, Cygnus spp	2005, Azerbaijan	HP	H5N1	De-feathering Meat processing	34
Poultry	Chickens and domestic ducks	1997–present, Asia and Africa	HP	H5N1	Caregiving Butchering De-feathering Meat processing Possibly consumption Unknown	15
	Chickens	2007, UK	LP	H7N2	Visiting bird market	106
	Chickens	2006, UK	LP	H7N3	Caregiving	106
	Chickens	2004, Canada	HP	H7N3	Caregiving Managing outbreak	106
	Chickens	2003, Netherlands	HP	H7N7	Caregiving Managing outbreak	106
	Chickens Turkeys	2002–2003, Italy	LP	H7N3	Managing outbreak	106
	Turkeys	2002, USA	LP	H7N2	Managing outbreak	106
	Domestic ducks	1996, UK	LP	H7N7	Caregiving	106
	Unknown	2007, Hong Kong	LP	H9N2	Unknown	55
	Unknown	2003, USA	LP	H7N2	Unknown	106
	Unknown	2003, Hong Kong	LP	H9N2	Unknown	55
	Unknown	1999, Hong Kong	LP	H9N2	Unknown	55
	Unknown	1998, China	LP	H9N2	Unknown	55

LP, low pathogenic; HP, highly pathogenic

Table 2. Summary of the pathogenesis characteristics of avian influenza virus infection in wild waterbirds, terrestrial poultry and humans

	Route of entry and transmission	Tissue tropism	Pathology and host responses	Immunity
Wild waterbirds	Fecal-oral (LPAIV) Oral and/or respiratory (HPAIV H5N1)	Intestinal tract (LPAIV) Respiratory tract, brain and other organs except the intestinal tract (HPAIV H5N1)	No or very mild degenerative lesions (LPAIV) From mild to severe lesions of necrosis and inflammation (HPAIV H5N1)	Low and transient humoral immunity Cellular immunity?
Terrestrial poultry	Fecal-oral and respiratory	Respiratory tract and possibly reproductive and urinary tracts (LPAIV) Respiratory tract, endothelium and other organs (HPAIV)	Mild lesions of necrosis and inflammation (LPAIV) Severe lesions of necrosis, inflammation, hemorrhage, edema (HPAIV)	Protective homosubtypic humoral immunity Cellular immunity?
Humans	Respiratory Ocular (H7) Potentially oral (HPAIV H5N1)	Respiratory tract Respiratory tract and other organs (HPAIV H5N1)	Mild to severe lesions of necrosis and inflammation	Protective humoral and cellular homosubtypic and heterosubtypic immunity

LPAIV, low pathogenic avian influenza viruses; HPAIV, highly pathogenic avian influenza viruses; H7, avian influenza viruses of the H7 subtype

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