Detection of Mycobacterium avium subsp. paratuberculosis in Cow Milk Using Culture and PCR methods



Mycobacterium avium subspecies paratuberculosis (MAP) is the cause of John’s disease also called
paratuberculosis. This is economically one of the important infectious diseases in cattle and ruminant
husbandry. This disease is manifested as granulomatosis entrocolitis, lymphadenitis and inflammation local
lymphatic vessels. The typical sign of this disease is progressive loss of weight. Considering the importance
of detection of this disease in this study, two methods, culture and PCR, were used for the identification of
this microorganism. In this study 100 milk samples from apparently healthy cows and 100 milk samples
from cows that have been suspicious of John’s disease were taken from in Sarab, East Azarbaijan, Iran.
Direct microscope observation after ziehl-neelsen staining was done. Then, bacterial culture on specific
medium was carried out, and finally, identification of Mycobacterium avium subsp. paratuberculosis was
examined using PCR and specific primers. Using direct observation, culture and PCR analyses showed that
from 100 healthy cow milk samples, 8, 9 and 12 samples were positive MAP for each method respectively.
The results of direct observation, culture and PCR analysis on affected cows were 15, 40 and 44,
respectively. The results of this study showed that culture and PCR analyses methods are important in the
identification of the causes of this disease. Therefore, considering the frequency of the disease in the studied
region, either of those methods can be used in the microorganism identification.