Influenza

Wild Birds in Live Birds Markets: Potential Reservoirs of Enzootic Avian Influenza Viruses and Antimicrobial Resistant Enterobacteriaceae in Northern Egypt

“…The same findings were previously reported in Egypt [26], where H5N1 and H9N2 viruses were detected in migratory mallards and were genetically closely related to AIV circulating in domestic poultry. In the same context, HPAI has been occasionally reported in wild birds near to affected poultry flocks, but these bird have played a minor or no role in the dissemination of the virus [30]. We believe that Northern shoveler acquire enzootic influenza infection via direct contact with domestic birds in LBM with the absence of clinical signs, which was previously reported [26].…”

Pathobiological Origins and Evolutionary History of Highly Pathogenic Avian Influenza Viruses

“…The initial clinical presentation in poultry had a mild course with an abrupt change to highly lethal, rapidly spreading disease very similar to our contemporary understanding of the origins of a HPAI virus through changes in the hemagglutinin (HA) proteolytic cleavage site of a H5 or H7 LPAI virus (Bosch et al 1979; Kawaoka and Webster 1985;Perdue et al 1996;Kaleta and Rulke 2008). The fowl plague cases from the 1880s to 1959 were exclusively H7N7 and H7N1 HPAI viruses, but in 1959, the first H5 HPAI virus appeared in chickens in Scotland, H5N1 (Kaleta and Rulke 2008;Swayne et al 2020). From the 1880s to 1959, fowl plague spread throughout Europe, Asia, and Africa and was reported from North and South America.…”

“…However, the presence of any insertion that lengthens the cleavage site but has not been previously reported should be discussed with an OIE Avian Influenza Reference Laboratory or Collaborating Centre before classifying the virus as LPAI or HPAI virus (OFFLU 2019). Although most of the HPAI chicken viruses emerged from LPAI precursors in aquatic wild birds, the emergence of HPAI viruses does not always occur in gallinaceous host (Swayne et al 2020). The detailed steps of how LPAI viruses evolve into HPAI viruses are not completely understood, but molecular techniques such as next-generation sequencing and reverse genetics have helped to identify the HA…”

“…A vian influenza (AI) viruses have their ancestry within the ecological niches occupied by aquatic birds, predominately of the orders Anseriformes and Charadriiformes, and these aquatic birds are the primordial reservoir of genes for all Influenzavirus A strains with the exception of the genetic material of H17N11 and H18N12 influenza A viruses, which have been detected only in bats (Webster et al 1992;Mehle 2014). Currently, AI viruses have surface proteins of any of the 16 different hemagglutinin (H1-16) and nine different neuraminidase (N1-9) subtypes (Swayne et al 2020). Based on their pathogenicity in chickens, most H1-H16 AI viruses cause mild respiratory, enteric, or reproductive diseases (i.e., low-pathogenicity avian influenza [LPAI]), whereas some of the H5 and H7 AI viruses cause deadly, systemic disease (high-pathogenicity avian influenza [HPAI]).…”

“…However, since 1959, with well-maintained unique virus isolates in archives, outbreaks caused by HPAI viruses have mostly arisen from virulence shifts by LPAI viruses with limited spread and eradication from poultry via stamping out programs. The major exception has been the A/goose/Guangdong/1/ 1996 (Gs/GD) lineage of H5, which arose in 1996 and has spread and been maintained in poultry and wild aquatic bird reservoirs until the current date, producing infections in poultry, wild birds, or humans in 84 countries in Asia, Africa, Europe, and North America (Röhm et al 1995;Swayne et al 2020). The first LPAI virus from poultry was identified in chickens in Germany in 1949 (Dinter virus, H10N7) (Swayne 2008a), and the first LPAI viruses in wild waterfowl (Slemons et al 1974) and pelagic seabirds (Downie and Laver 1973) were identified in 1972, although antibodies to Influenza-virus A had been detected in migratory waterfowl as early as 1968 (Easterday et al 1968).…”