STUDY ON PATHOLOGY OF TERMINAL ILEUM IN GOATS WITH PARTICULAR EMPHASIS ON PARATUBERCULOSIS
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Date
2014-07-19
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CSKHPKV, Palampur
Abstract
The present study was conducted to assess the prevalence of paratuberculosis in goats (Gaddi and non-descript)
reared in Himachal Pradesh and slaughtered for table purpose, using different diagnostics such as histopathology,
ZN staining, ELISA and AGID. A total of 68 goats (57 females and 11 males) slaughtered during September, 2013
to March, 2014 were investigated. Forty six out of 68 samples were collected from slaughter places in and around
the Palampur and 22 from Shimla. The status of Johne’s disease in goats was investigated using gross and
histopathological examination, ZN staining of cytology and tissue sections, and serological detection of MAP by
ELISA and AGID. The tissue samples collected from terminal ileum and associated ileo-caecal and mesenteric
lymph nodes were investigated. The serum samples collected from the same animal were subjected to detect the
presence of antibodies to MAP by ELISA and AGID. The gross lesions were mainly observed in the terminal
ileum especially near ileo-caecal junction. The most significant gross findings were mild to moderate, focal or
diffuse thickening of terminal ileum especially at ileo-caecal junction, with or without corrugations. In most of the
animals with gross lesions, ileo-caecal valves were consistently thickened. The ileo-caecal and mesenteric lymph
nodes were severely enlarged and were found to be oedematous. Cut surfaces of lymph nodes revealed grayish
white patchy areas in the cortex and its delineation from the medullary region was usually indistinct. In most of the
cases, mesenteric lymph nodes were fused to give knotted appearance. Histopathological examination of tissue
sections (terminal ileum and associated lymph nodes) revealed variable grade of lesions indistinguishable from
paratuberculosis in 39 (57.35%) out of 68 goats. Histologic lesions were classified into four grades grade I (least
severe) to IV (most severe) on the basis of types and density of cellular infiltrate (lymphocytes, macrophages and
epithelioid cells). Out of 68 animals, 9 (13.2%), 17 (25.0%), 9 (13.2%) and 4 (5.8%) were showing lesions of grade
I, II, III and IV, respectively. In general, the lesions were characterized on the basis of infiltration of mononuclear
cells consisting of lymphocytes, macrophages and epithelioid cells in the lamina propria and submucosa of
intestine and cortex, paracortex and medulla of lymph node.The affected part of the intestine revealed degeneration
of lining epithelial cells of villi. The villi exhibited variable changes including its distortion, thickening and fusion.
On ZN staining of impression smears, 14 (20.58%), 12 (17.64%) and 9 (13.23%) out of 68 cases of ileum, ICLN
and MLN respectively, revealed presence of acid-fast bacilli individually or in clusters indistinguishable from
MAP. On ZN staining of tissue sections, 9 (13.23%), 10 (14.7%) and 5 (7.35%) out of 68 cases of ileum, ileocaecal
and mesenteric lymph nodes, respectively, revealed presence of acid-fast bacilli individually or in clusters in
the epithelioid cells indistinguishable from MAP. Total 14 (20.58%) cases, out of 68 were found positive on ZN
staining of tissue sections and out of these one was multibacillary (7.14%) and rest 13 (92.8%) were of
paucibacillary type. Out of 9 grade-I cases, 6 (66.6%) and 5 (56.0%) were diagnosed positive by ELISA and
AGID, respectively and none by cytology and ZN staining of tissue sections. Out of 17 grade-II cases, 5 (29.41%),
4 (23.52%), 10 (58.8%) and 9 (52.94%) were found positive by cytology, ZN staining of tissue sections, ELISA
and AGID respectively. Out of 9 grade-III cases, 8 (88.8%), 6 (66.6%), 9 (100%) and 7 (77.7%) were diagnosed
positive by cytology, ZN staining of tissue sections, ELISA and AGID, respectively. All grade-IV cases (4) were
found positive in ZN staining of cytology, tissue sections as well as on ELISA, however, AGID detected 3 out of 4
animals positive for grade IV lesions. Thus histopathology could detect more number of cases in early stage of
disease, while other tests (ZN staining, ELISA and AGID) detected more cases in later stages.
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