INVESTIGATION ON THE OCCURRENCE OF PARATUBERCULOSIS IN APPARENTLY HEALTHY SHEEP AND GOATS SLAUGHTERED ON BISHOFTU ELFORA, MOJO MODERN AND ORGANIC EXPORT ABATTOIRS, CENTRAL ETHIOPIA
No Thumbnail Available
Date
2015-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
A cross sectional study was conducted from October 2014 to June 2015 to investigate the
occurrence of paratuberculosis among apparently healthy sheep and goats slaughtered in
Bishoftu ELFORA Export Abattoir, Mojo Modern Export Abattoir and Organic Export
Abattoir, using gross pathology, histopathology, Ziehl-Neelsen (ZN) staining and
bacteriological culture of tissue lesions from paratuberculosis suspected animals. Based
on gross pathological examination, the prevalence of paratuberculosis was 5.21%
(20/384) (95% CI=2.8-7.4) in sheep and 3.4% (26/768) (95% CI=2.1-4.7) in goats.
Association of risk factors including species, age and origin of the animal with the
occurrence of gross lesion showed statistically insignificant difference among the groups
(P>0.05). However, a relatively higher prevalence was observed in sheep, age group of
≥2 years and in sheep originated from Borana. Out of 13 tissue samples from each
species, histopathological examination revealed microscopic lesions consistent with
paratuberculosis in 84.62% (11/13) of sheep and 76.9% (10/13) of goats, and the lesions
were characterized by diffuse infiltration of many lymphocytes accompanied with few
macrophages and epithelioid cells. Necrotic foci surrounded by lymphocytes,
macrophages and epithelioid cells were observed in lymph nodes of 15 % (2/13) sheep
and 23 % (3/13) goats. Grading of histological lesions based on the type and amount of
cellular infiltrate revealed that all positive cases of sheep and goat were categorized in
grade 3c lesion type and diffuse lymphocytic lesion type, respectively. On direct ZN
staining of 46 tissue samples (20 sheep; 26 goats), acid fast positivity was recorded in 16
(80%) sheep and 14 (53.8%) goats. Out of 46 tissue samples (20 sheep; 26 goats)
cultured on Herrold’s egg yolk media (HEYM) and Lowenstein-Jensen (LJ) media with
and without 1% ferric ammonium citrate, Mycobacterium avium subspecies
paratuberculosis (MAP) was isolated from 2 (10%) sheep and 1 (3.8%) goat on ferric
ammonium citrate (1%) supplemented media and all isolates were acid fast positive.
Isolated colonies were confirmed as MAP by ferric ammonium citrate dependence, their
long incubation period, colony characteristics and their morphology on ZN stained
smears. A linearly weighed kappa coefficient of 0.3 was obtained between histopathology
xii
and ZN staining, indicating fair agreement between the two tests. In conclusion the
present study on sheep and goat paratuberculosis using gross pathology, histopathology,
ZN staining and culture techniques revealed the occurrence of the disease in apparently
healthy sheep and goats in Ethiopia. This result warrants the need for further
investigation on the epidemiology, characterization of the causative agent and
assessments of the economic impact of paratuberculosis on small ruminants of Ethiopia
in order to design feasible control strategies.
Description
MsC Thesis
Keywords
Culture, Goat, Gross pathology, Histopathology, Paratuberculosis