Etiology and pathology of epidemic outbreaks of avian influenza H5N1 infection in Egyptian chicken farms

Abstract

Epidemic outbreaks of avian influenza (AI) virus H5N1 have been frequently reported in Egypt during the last nine years. Here we investigate the involvement of AI H5N1 in outbreaks of acute respiratory disease that occurred in several commercial chicken farms in Egypt in 2011, and we describe to the pathology caused by the virus in the course of the outbreak.Twenty-one chicken farms with history of acute respiratory symptoms and high mortalities were screened for AI H5N1. Virus identification was based on hemagglutination inhibition test, and PCR detection and sequencing of the hemagglutinin and neuraminidase genes. Virus distribution was determined by immunohistochemical staining of AI antigens in organs of infected birds. Standard H&E staining was performed for histological examination of affected organs.Eighty-one % of the examined birds, representing 100% of the screened farms, were positive for AI H5N1 virus. Phylogenetic analysis of the hemagglutinin and neuraminidase genes of the isolated virus reveals its affiliation to clade 2.2.1. Viral antigens were localized in the endothelial cells of the heart, liver, lungs and skin, where pathological lesions including congestion, hemorrhages, multifocal inflammation and necrosis were concurrently observed. According to the pattern of the viral antigen and lesion distribution in the visceral organs, we suggest cardiovascular and circulatory failures as the probable cause of death during these outbreaks. In conclusion, the present study further confirms the epidemic status of AI H5N1 virus in Egypt and reveals the highly pathogenic nature of the local isolates.

The Thrift of Avian Influenza in Indonesia

“…Clinical signs and pathological features of H5N1 in layer chickens from East Java, Central Java, West Java and Yogyakarta during 2003-2005 outbreaks have demonstrated depression, loss of appetite, neurologic disorder, respiratory disorder, egg production drop and diarrhoea [54]. These clinical signs were similar to previously described infections naturally or experimentally with highly pathogenic avian influenza virus in domestic poultry [44,45,51,55,56].…”

“…On post-mortem examination of infected chicken showed severe subcutaneous haemorrhages, oedema in the wattles, head, neck, and the leg shanks appeared haemorrhages [55]. However, Mutinelli et al [45] and Elbers et al [57] also described peritonitis; haemorrhage, enlarged and hardened of pancreas; enlarged…”

“…The Thrift of Avian Influenza in Indonesia DOI: http://dx.doi.org /10.5772/intechopen.85105 with whitish and dark brown haemorrhage of liver areas. In a few cases, proventriculus and ventriculus showed petechial haemorrhages [45,55,57], haemorrhages of comb and wattles, ecchymose haemorrhages in the skin of the breast and abdomen [47]. Similar lesions such as cyanotic wattles, swollen head and comb, haemorrhages in the skeletal muscles, abdominal fat, proventriculus and feet were also observed in chicken during 2003-2005 Avian Influenza outbreaks in Indonesia [54].…”

“…Histopathological findings of HPAIV-infected chicken and turkey were dominated by acute haemorrhages (skin, under serous membrane, mucosae and pectoral muscles), oedema (skin of head, neck, legs and lungs) and necrosis (skin, pancreas, spleen and heart) [42,46,49,55,[62][63][64][65][66]. The comb and wattles showed markedly severe cellulitis associated with congestion, oedema and mild heterophilic infiltration in the dermis and subcutis [55].…”

“…Histopathological findings of HPAIV-infected chicken and turkey were dominated by acute haemorrhages (skin, under serous membrane, mucosae and pectoral muscles), oedema (skin of head, neck, legs and lungs) and necrosis (skin, pancreas, spleen and heart) [42,46,49,55,[62][63][64][65][66]. The comb and wattles showed markedly severe cellulitis associated with congestion, oedema and mild heterophilic infiltration in the dermis and subcutis [55]. Lymphocytic meningo-encephalitis and meningo-encephalomyelitis with multifocal gliosis, degeneration of neuron, necrosis and neuronophagia, as well as mild-to-moderate perivascular cuffs, with predominance of macrophages and lymphocytes in both grey and white matter in the majority of brain region [60,67,68].…”