Molecular diagnosis of avian respiratory diseases in commercial broiler chicken flocks in province of Najaf, Iraq

Avian influenza virus subtype 9 and Newcastle virus have been recognized as the most important pathogens in poultry. In Najaf governorate, Iraq, many chickens’ flocks suffered from high mortality (about 30 to 70%) and respiratory signs. In this study, trachea swabs and tissue specimens from 53 commercial broiler chicken flocks suffering from respiratory diseases were tested initially by rapid test for antigen influenza type A and by reverse transcription polymerase chain reaction (PCR) for avian flu virus type A, H5, H7, H9, and Newcastle disease virus (NDV). The reverse transcription PCR results showed that 75% of these flocks were infected with both avian flu virus type H9 and NDV whereas 25% of them were infected only by H9. On the other hand, all flocks were negative for subtypes H5 and H7. Our data showed that aforementioned respiratory pathogens were the most important agents of respiratory diseases giving high mortality in broiler chicken in the area of the study.   Key words: Respiratory diseases, avian flu, broiler chicken, molecular diagnosis, Iraq.