Estimation of percentage of morbidity and mortality due to avian influenza (H9) at commercial poultry layer farms of Lahore

Abstract

The current study was aimed at the estimation of the percentage of morbidity, mortality and potential risk factors associated with the avian influenza virus (AIV) H9 at commercial layer farms of District Lahore, Pakistan. Samples collected included blood samples and tracheal/oropharyngeal swabs from sick birds and tissue samples (trachea & lungs) of dead birds. Sera were tested by Hemagglutination Inhibition Test (HI) using the positive control antigen of H9. Tracheal/oropharyngeal swabs and tissue samples were processed by real-time RT-PCR (rRT-PCR). Out of 50 layer farms, 16 farms were positive for antibody titer against the AIV H9. Out of a total of 116 individual sera samples, only 20 were positive for AIV H9 by HAI test. The seropositivity was 17.24% (95% CI: 10.86-25.36). Out of 50 farms, samples of sick birds from 7 farms tested positive, while samples of dead birds from 8 farms tested positive by rRT-PCR for the M gene of AIV. The percentage of morbidity was estimated to be 14% (95% CI: 5.8-26.7). The percentage of mortality was estimated to be 16% (95% CI: 7.17-29.11). The potential risk factors associated with AIV were age, season of infection, feed and water shared with sick birds and source of drinking water. The results showed AIV is circulating and that commercial layer farms are a hotspot of AIV infection.