Comparison of molecular and serological isolation methods to identify pigeons suspected of having avian tuberculosis

Tuberculosis is one of the oldest infectious zoonotic diseases. The importance of avian tuberculosis and the growing risk of the disease in human societies have provided a double incentive for rapid diagnosis of the disease. Mycobacterium avium subsp. avium is the most important cause of disease in poultry. Sampling for the present research was done during 2018-2019. Based on clinical signs and poor physical condition, 101 pigeons suspected of having tuberculosis were selected from different herds. First, blood samples were taken from pigeons for serum preparation. Then pigeons were euthanized and necropsy was performed and tissue samples were taken for culture and molecular tests. The samples were cultured in three specific media: Lunstein-Johnson with glycerin, Lunstein-Johnson with pyruvate and Heroldegg. Molecular analysis of samples was conducted using 16S rRNA, IS1245, and IS901 primers. Serum samples were analyzed for antibodies against Mycobacterium avium using a specifically designed ELISA system. Based on culture and molecular identification, 39 isolates from Mycobacterium avium subsp. avium were isolated. Contamination of 13 pigeons with Mycobacterium avium subsp. avium was detected using the specifically designed ELISA system. According to the results, the sensitivity of the culture and PCR methods was higher than the specifically designed ELISA system. However, due to the significant relationship between these three methods, it seems that the ELISA system can be used to screen flocks in the early stages of the disease.