Histopathological and serological studies on paratuberculosis in cattle and buffaloes

Paratuberculosis (Johne's diseases) is responsible for massive economic losses to dairy industry, both in the industrially advanced as well as in the developing countries. To detect its occurrence in cattle and buffaloes locally, blood and tissue samples from clinically weak and grossly suspected slaughtered animals were collected from two abattoirs of Jhang, municipal area, Pakistan. Acid-fast smear staining, gross/histopathology and indirect ELISA was done for the detection of Mycobacterium avium subsp. paratuberculosis (MAP). Total 134 samples illustrating gross pathological lesions were collected, only 11.19% (cattle: 6.67%, buffaloes: 12.5%) showed acid fast bacilli through smear staining and were taken as confirmed cases. Thickening of intestines alone was not a reliable indicator of Johne's disease. Tissue sections from intestines and mesenteric lymph nodes from these acid fast positive animals were stained with hematoxylin & eosin (H&E) and Ziehl Neelsen (ZN) methods. Sum of (15/134) impression smear staining as well as (15/15) tissue sections of the intestines were found ZN positive, and only 6.7% of impression smears and 100% of tissue sections of mesenteric lymph nodes showed acid fast bacilli. Through ELISA, two cattle and five buffaloes (07/134) gave positive optical densities, while one cattle and seven buffaloes (08/134) were judged as doubtful. It is concluded that infection of MAP can be identified by histopathology and ELISA. The present study was the first record of paratuberculosis among the dairy animals slaughtered at Jhang abattoirs. The objective was to compare different methods for the diagnosis of Johne's disease.