[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]
Transbound Emerg Dis. 2019 Jul 11. doi: 10.1111/tbed.13281. [Epub ahead of print]
Respiratory disease due to mixed viral infections in poultry flocks in Egypt between 2017 and 2018: Upsurge of highly pathogenic avian influenza virus subtype H5N8 since 2018.
Hassan KE1,2, El-Kady MF2, El-Sawah AAA2, Luttermann C3, Parvin R1,4, Shany S2, Beer M1, Harder T1.
Author information: 1 Institute of Diagnostic Virology, Friedrich-Loeffler-Institute, Greifswald-Riems, Germany. 2 Department of Poultry Diseases, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, Egypt. 3 Institute of Immunology Virology, Friedrich-Loeffler-Institute, Greifswald-Riems, Germany. 4 Department of Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh, Bangladesh.
For several years, poultry production in Egypt has been suffering from co-circulation of multiple respiratory viruses including highly pathogenic avian influenza virus (HPAIV) H5N1 (clade 188.8.131.52) and low pathogenic H9N2 (clade G1-B). Incursion of HPAIV H5N8 (clade 184.108.40.206b) to Egypt in November 2016 via wild birds followed by spread into commercial poultry flocks further complicated the situation. Current analyses focussed on 39 poultry farms suffering from respiratory manifestation and high mortality in six Egyptian governorates during 2017-2018. Real-time RT-PCR (RT-qPCR) substantiated the co-presence of at least two respiratory virus species in more than 80% of the investigated flocks. The percentage of HPAIV H5N1-positive holdings was fairly stable in 2017 (12.8%) and 2018 (10.2%), while the percentage of HPAIV H5N8-positive holdings increased from 23% in 2017 to 66.6% during 2018. The proportion of H9N2-positive samples was constantly high (2017:100% and 2018:63%), and H9N2 co-circulated with HPAIV H5N8 in 22 out of 39 (56.8%) flocks. Analyses of 26 H5, 18 H9 and 4 N2 new sequences confirmed continuous genetic diversification. In silico analysis revealed numerous amino acid substitutions in the HA and NA proteins suggestive of increased adaptation to mammalian hosts and putative antigenic variation. For sensitive detection of H9N2 viruses by RT-qPCR, an update of primers and probe sequences was crucial. Reasons for the relative increase of HPAIV H5N8 infections versus H5N1 remained unclear, but lack of suitable vaccines against clade 220.127.116.11b cannot be excluded. A reconsideration of surveillance and control measures should include updating of diagnostic tools and vaccination strategies.
© 2019 Blackwell Verlag GmbH.
KEYWORDS: Egypt; Highly pathogenic avian influenza; co-infection; control; diagnostic tools; reassortant viruses
PMID: 31297991 DOI: 10.1111/tbed.13281
Keywords: Avian Influenza; H5N1; H5N8; H9N2; Poultry; Egypt.