First Year of the Highly Pathogenic Avian Influenza H5N1 Outbreak in Egypt: Rapid Antigenic/Molecular Diagnosis and Virus Isolation

摘要

In mid-February 2006, an outbreak of Highly Pathogenic Avian Influenza (HPAI) H5N1 affected the commercial poultry production sector and backyards in Egypt and resulted in magnificent socioeconomic losses. The present study was designed for detection, isolation and characterization of Avian Influenza Viruses (AIV) circulating among different poultry species during the first year of the outbreak. A total of 22 commercial poultry farms (16 chicken, 5 ducks and 1 quails) and 5 zoo birds were examined for such purpose. While, no influenza viruses were detected in zoo birds, 68% of the commercial poultry farms located in seven Egyptian governorates were positive to AIV and 53.3% of them were subtyped as H5. Virus isolation in SPF chicken embryos was successful for nine samples from the first egg passage. Molecular characterization of the viral RNA, in the harvested allantoic fluid by multiplex RT-PCR, confirmed the virus identity. On the basis of the OIE criteria of pathogenicity and the observed mortality profile, the AIV isolated during the first wave of the outbreak was identified as highly pathogenic, where the Intravenous pathogenicity index (IVIP) score was 2.83 and the mortality rate was 100%. In conclusion, this study outlines the major implication of subtype H5 HPAI in field affections during the first year of the outbreak. Additional involvement of other influenza A viruses and probably haemagglutinating respiratory agents can not be excluded.