Abstract

The current study aimed to identify the respiratory problems in poultry farms located in the north coast of Egypt from October 2018 to November 2019. A total of 89 poultry flocks (79 broilers, 5 layers, 3 ducks, and 2 turkeys) were investigated for four major viral respiratory pathogens, namely avian influenza (AI) H9N2, AI H5 subtypes, Newcastle Disease (ND), and Infectious Bronchitis (IB) viruses. All 89 flocks were subjected to real-time PCR to investigate AI H9N2 virus. The samples of 31, 43, and 15 out of 89 flocks were selected for the investigation of ND, IB, and AI H5 subtypes viruses, respectively, using real-time PCR. Sample selection was performed according to the mortalities, clinical signs, and post mortem lesions. The positive findings indicated that 22 out of 89 flocks were positive for AI H9N2 virus (2 layers + 20 broilers), 32 out of 43 flocks were positive for IB virus (2 layers + 30 broilers), 24 out of 31 flocks were positive for ND virus (1 Duck + 1 layer+ 22 broilers) and 9 out of 15 flocks were positive for AI H5N8 virus (1 turkey + 1 duck + 7 broilers). Partial sequencing for selected isolates of six ND, five IB, four H9N2, and three H5N8 viruses was applied, then nucleotide sequences were accessed on GenBank. Six ND isolates belonged to genotype Vӏӏ viruses circulating in Egypt. Two IB isolates were related to the classical strain circulating in Egypt, while the other three IB isolates belonged to EGY/Variant ӏӏ. Four H9N2 AI isolates were related to G1-lineage of H9 viruses circulating in the Middle East and Egypt. Three H5N8 AI isolates belonged to the highly diverse clade 2.3.4.4.b viruses circulating in Egypt. It was concluded that ND and IB viruses isolated in this study were not related to their vaccinal strains. Also, AI H5N8 circulating alone in affected flocks while AI H9N2 circulating alone and/or mixed with either IB or ND viruses. Finally, there is a need to devise a complete strategy to control the isolated respiratory viruses on the north coast of Egypt.