Comparative diagnosis of Mycobacterium avium subspecies paratuberculosis in the tissues of clinical and subclinical sheep of paratuberculosis endemic farm

AbstractParatuberculosis (Johne ’s disease) is the chronic infectious granulomatous enteritis of ruminants caused byMycobacterium avium subspeciesparatuberculosis. Due to the lack of definite diagnostic tests, the early detection of the disease is difficult. The present study was undertaken to assess comparative efficacy of diagnostic methods routinely used in the identification and confirmation ofMycobacterium avium subspeciesparatuberculosis (MAP) in the tissue samples of naturally infected clinical and subclinical sheep. The ileum and mesenteric lymph node (MLN) tissues were collected from 20 paratuberculous sheep from organized farm of Rajasthan. These animals were further classified as paucibacillary (PB) (n = 8) or multibacillary (MB) (n = 12) on the basis of histopathological findings and mycobacterial loads. The ileum and MLN sections from PB and MB and uninfected control groups were tested by indirect immunoperoxidase technique (IPT), Ziehl Neelsen’s (ZN) method, bacterial culture, IS900 PCR and 251 gene PCR. In PB sheep, IPT and ZN were positive in 87.5 and 50% of intestinal sections and 75 and 37.5% of MLN sections, respectively. In MB sheep, IPT and ZN had equal sensitivity. The overall sensitivity of IPT was found to be superior (95%) than ZN method (80%) in demonstration of acid-fast bacteria in intestinal tissues. On the bacterial cultural examination of the intestinal and MLN tissues using Herrold ’s egg yolk medium, MAP was isolated in eight (66...
Source: Comparative Clinical Pathology - Category: Pathology Source Type: research