Description of the Infectious Status in Murrah Buffalo Herd Naturally Infected by Mycobacterium Avium Subsp. Paratuberculosis (map) in Tamilnadu

The surveillance for paratuberculosis in Livestock Research Station (LRS), Kattupakkam revealed 12 sero-reactors in a dairy buffalo herd of 23 animals that had no clinical signs of Mycobacterium avium subsp paratuberculosis (MAP) infection. Paratuberculosis has been a clinical problem in sheep and goats for the recent years in this farm. All the 12 buffalos were culled and a thorough investigation of the infection status was conducted by IFN-γ immunoassay, serological assay (ELISA), and pathological and bacteriological examination. By IFN-γ immunoassay, 8 animals proved positive, 3 animals proved weakly positive and whereas by serological assay, all the 12 animals proved positive. Histopathological lesions suggestive of paratuberculosis were diagnosed in 10 animals aged between 6 and 8 years. Seven out of 12 animals of which paratuberculosis were verified by bacteriology had positive sero reaction in the IFN-γ immunoassay. Infection status could be confirmed by isolation of the MAP in 7 out of 12 animals; however the polymorphism of the bacterial isolates could not be established in this study. Eventually, many animals being positive in one or both of the immunological tests it indicative of the herd were heavily infected and maintained in subclinical form of MAP without pronounced clinical signs. In conclusion of this study it emphasized that cross reaction with other Mycobacteria might have been caused some of the immunoreactions in these animals.