Serological surveillance reveals widespread influenza A H7 and H9 subtypes among chicken flocks in Egypt

Abstract

Multiple avian influenza viruses' subtypes are circulating worldwide possessing serious threat to human populations and considered key contributors to the emergence of human influenza pandemics. This study aimed to identify the potential existence of H7 and H9 avian influenza infections circulating among chicken flocks in Egypt. Serum samples were collected from chicken flocks that experienced respiratory distresses and/or variable mortality rates. H7 and H9 virus infections were screened by haemagglutination inhibition assay using chicken erythrocytes. Serum samples were collected from 9 broiler, 12 breeder and 18 layer flocks. Out of 1,225 examined sera, 417 (34 %) from 14 flocks and 605 (49.4 %) from 21 flocks were found positive for H7 and H9, respectively. Prevalence of both H7 and H9 antibodies were higher in layer followed by breeder then broiler flocks. Special consideration should be paid to control influenza viruses in Egypt, as pandemic influenza strains may develop unnoticed given the presence of subclinical infections, and the possibility of re-assortment with the prevailing endemic H5N1 virus strains in Egypt do exist.

Evolutionary trajectories and diagnostic challenges of potentially zoonotic avian influenza viruses H5N1 and H9N2 co-circulating in Egypt

“…These mutations have not been detected in any other H9N2 virus from Egypt so far, and due to the conservation of chemical properties, their effect on antigenicity is unclear. Also unique to Egyptian H9N2 viruses M2 V27I presumed to be associated with amantadine resistance was detected in three isolates; no further amantadine resistance markers were present (Belshe et al, 1988) Previously undescribed in the HA of Egyptian H5N1 viruses was an additional, sixth, PGS at (Afifi et al, 2013). BEAST analysis carried out here narrowed the possible introduction date of H9N2 viruses into Egypt to July-August 2009 (Fig.…”

Epidemiology, ecology and gene pool of influenza A virus in Egypt: Will Egypt be the epicentre of the next influenza pandemic?

“…Also, serological investigation revealed that the H9N2 virus was wide-spread in commercial farm settings between February 2009 and April 2012. 68 About 50% (605/ 1225) of collected sera from 39 chicken flocks were tested positive for H9 subtype. 68 In another study, 165 commercial flocks and only 3 cases of backyards were found positive.…”

“…68 About 50% (605/ 1225) of collected sera from 39 chicken flocks were tested positive for H9 subtype. 68 In another study, 165 commercial flocks and only 3 cases of backyards were found positive. 16 In 2011-2013, one study identified H9N2 in 24 out 60 broiler, one out of 5 layer and one out of 5 breeder flocks 69 and the second study isolated the virus from 22 broiler flocks.…”

“…16 In 2011-2013, one study identified H9N2 in 24 out 60 broiler, one out of 5 layer and one out of 5 breeder flocks 69 and the second study isolated the virus from 22 broiler flocks. 70 While the majority of infected chickens showed respiratory distress 66,68 and there was a decrease in egg production in breeder and layer flocks, 68 infected quails and some broiler flocks were clinically healthy. 16,67,70 Importantly, co-infection or prior infection with H5N1 and H9N2 was also reported in many cases in poultry in Egypt.…”

“…73 In 2009-2010, antibodies against H7 virus were detected in 14/39 commercial chicken flocks. While the highest prevalence of positive samples was from layer flocks (9/18) followed by breeders (3/12) and broilers (2/ 9), 68 there is no report for virus isolation in commercial or backyard poultry to date.…”