Prevalence of Avian Influenza H5, H7 and H9 Viruses in Commercial Broilers at Karachi, Pakistan

Abstract

Avian influenza viruses (AIVs) are highly contagious and pathogenic viruses that caused severe disease in poultry and are potentially zoonotic. Since last decade the outbreaks of AIVs have been increased globally including Pakistan. Therefore this study was conducted to determine the prevalence of avian influenza H5, H7 and H9 viruses in broilers at Karachi, Pakistan. A total of 1920 samples, including each of 960 blood samples and tracheal swabs were collected from broilers and tested through hemagglutination inhibition (HI), AIV-ELISA and RT-PCR. The HI test revealed a significant (P<0.01) difference in the seroprevalence of H9 virus (40.11%), H5 virus (16.88%) and H7 virus (6.25%) respectively. The mean antibody titer against H5, H7 and H9 virus was 4.87, 3.72, and 5.31 log2 respectively. AIV-ELISA revealed that overall prevalence of AIV viruses was 8.44% which was subtyped through RT-PCR that revealed the higher occurrence of H9 virus (5.33%) as compared to H7 (1.16%) and H5 (0.31%). However, the coin-fections of H7/H9 (0.73%) was higher than H5/H9 (0.21%) and H5/H7/H9 (0.21%). In conclusion, the H5, H7, and H9 avian influenza viruses are circulating in broilers of Karachi, Pakistan; moreover, the prevalence of H9 virus and the H7/H9 coinfections are common than other subtypes of AIV.