Pathological and Molecular Characterization of H5 Avian Influenza Virus in Poultry Flocks from Egypt over a Ten-Year Period (2009–2019)

Abstract

Avian influenza virus (AIV) remains one of the enzootic zoonotic diseases that challenges the poultry industry in Egypt. In the present study, a total of 500 tissue samples were collected from 100 chicken farms (broilers and layers) suspected to be infected with AIV through the period from 2009 to 2019 from Dakahlia governorate, Egypt. These samples were pooled in 100 working samples and screened for AIV then the positive samples were subjected to histopathological examination combined with real time-polymerase chain reaction (RRT-PCR). RRT-PCR positive samples were also subjected to conventional reverse transcriptase-polymerase chain reaction (RT-PCR) for detection of H5 AIV and some of these resulting positive samples were sequenced for detection of the molecular nature of the studied virus. Interestingly, the histopathological examination revealed necrotic liver with leukocytic infiltration with degenerative changes with necrotic pancreatitis, edema, and intense lymphoid depletion of splenic tissue and hyperplastic tracheal epithelium. Likewise, edema and congested sub mucosal blood vessels and intense bronchial necrosis with hyalinized wall vascular wall and heterophils infiltration were reported. Pneumonic areas with intense leukocytic aggregation mainly and vasculitis of the pulmonary blood vessels were also detected in lung. Collectively, these significant pathological changes in examined tissues cohered with AIV infection. Regarding the molecular characterization, 66 samples were positive for AIV by RRT-PCR and 52 of them were positive for H5 AIV by RT-PCR. The phylogenetic analysis revealed that the H5 viruses identified in this study were aligned with other Egyptian H5N1 AIVs in the Egyptian sub clade 2.2.1, while some of the identified strains were aligned with other Egyptian H5N8 strains in the new Egyptian sub clade 2.3.4.4. Taken together, our present findings emphasize the wide spread of AIV in Egypt and the importance of developing an efficient surveillance and periodical screening program for controlling such disease of public health concern.

Molecular detection of highly pathogenic avian influenza H5N8 in commercial broiler chicken farms from 2019 to 2022

“…The clinicopathological pictures that have been noticed in H5N8-positive broiler farms in the present study were mainly respiratory and nervous signs, including various degrees of tracheitis, enteritis, pneumonia, proventricular hemorrhage, and splenic necrosis. Similar findings have been recorded by Mosad et al (2020) in infected chickens with HPAI H5 virus in Dakhalia governorate, Egypt.…”

Spatiotemporal analysis of highly pathogenic avian influenza (H5N1) outbreaks in poultry in Egypt (2006 to 2017)

“…Although there is no significant data on HPAI H5N1 for 2018 and 2019 [ 33 ], several studies declared a widespread of the virus among poultry flocks in Egypt [ 34 ]. Infection in backyard poultry is usually associated with mild or no symptoms [ 2 ], calling for the need to develop an efficient surveillance program and investigate the effectiveness of the current implemented control measures [ 34 ]. The impact of vaccination on the temporal and spatial distribution of the outbreaks in endemic areas is debated [ 35 ].…”

Newcastle Disease Genotype VII Prevalence in Poultry and Wild Birds in Egypt

“…More than 250 domestic and wild bird species have been shown to be susceptible to NDV infection with varying clinical forms [ 13 , 14 , 15 , 16 ]. However, virus transmission among wild birds possesses serious risk for both poultry and other wild bird populations [ 17 , 18 ]; virus adaption can encourage new susceptible host species, posing a greater threat to local as well as wider geographical regions [ 17 , 18 , 19 ]. Mansour et al [ 20 ] reviewed the clinical disease, epidemiology, and evolutionary perspective, of NDV among domesticated and wild birds in the view of available research work publications.…”