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Evaluating Diagnostic Tests To Assess The Epidemiological Status Of Bovine Tuberculosis

KrishiKosh

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Title Evaluating Diagnostic Tests To Assess The Epidemiological Status Of Bovine Tuberculosis
 
Creator Yesuf, Faris Delil
 
Contributor Ganesan, P.I.
Kumanan, K.
Ronald, B. Samuel Masilamoni
Vijaya Bharathi, M.
 
Subject Bovine tuberculosis
Single Intradermal Comparative Cervical Tuberculin test
Gamma Interferon test
Enzyme-Linked Immunosorbent Assay
Polymerase Chain Reaction
Ziehl–Neelsen staining
Visible lesions
 
Description Evaluation and assessment of the epidemiological status of bovine
tuberculosis (bTB) using different diagnostic techniques have been carried out in
organized, unorganized dairy farms and slaughter house materials in urban and
suburban areas.
In organized farms bTB diagnostic tests including Single Intradermal
Comparative Cervical Tuberculin (SICCT) test, Gamma Interferon (IFN-γ) assay,
Enzyme Linked Immunosorbent Assay (ELISA) and Polymerase Chain Reaction
(PCR) were employed. From these organized farms, 195 animals were screened
by SICCT test of which 7(4.1%) were reactors. Skin test reactivity has been
compared among the two management systems adopted by organized farms
including those practicing semi-grazing and zero- grazing. Higher percentage of
animals from semi-grazing type of management i.e.7 out of 114 (6.1%) were
found reactors to SICCT test compared with zero-grazing 1 out of 81 (1.2 %).
A total of 117 animals from the same organized farms that were screened
by SICCT test were also assessed by IFN-γ assay for bTB and 13 animals (11.1
%) were positive. The prevalence figure among the two management systems
using IFN-γ assay compared. As that of SICCT test, more number of animals, 9
out of 36 (25%) from semi-grazing type of management were positive compared
with zero-grazing which was 4 out of 81 animals (4.9%).
Comparison of SICCT test and IFN-γ assay indicated 5 (4.3%) animals to
be positive by both tests and 101 (86.3%) negative by both tests with 90.6%
concordance. The two tests showed moderate agreement (kappa=0.44).
Comparison of SICCT test and ELISA displayed 3 (2.6%) animals to be
positive by both tests and 105 animals (89.7%) negative by both tests with 92.3%
concordance. The two tests showed moderate agreement (kappa= 0.36).
With regard to ELISA, from the same organized farms that were screened
by SICCT test and IFN-γ assay, 117 parallel sera were assessed for bTB antibody
using commercial kit. Of 117 animals, 8 (6.8 %) were seropositive.
Comparison of ELISA and IFN-γ assay revealed that 2 animals (1.7%) to
be positive by both tests and 99 animals (84.6) negative by both tests with 86.3%
concordance. The two tests showed slight agreement (kappa=0.13).
The overall bTB prevalence in organized farms by using these three
diagnostic tests: SICCT test, IFN-γ assay and ELISA in the current investigation
with interpretation of positive if an animal is positive by any of these tests was
15.9%.
In unorganized farms, ELISA and PCR using milk and nasal swabs were
employed during the current investigation. Out of 193 sera, 101 were bovine
samples that attended MVC Teaching Hospital and 92 from small holder dairy
farms in Salem district, 11 (10.9%) and 3 (3.3%) animals were seropositive,
respectively. Similarly, 207 milk samples, 167 from MVC Teaching Hospital outpatient
unit and 42 from small holder dairy farms from Salem district that were
assessed for MTC by IS6110 PCR. In this study, 39 (23.6%) from MVC and 3
(7.1%) from Salem district were shedding organisms in milk. On the other hand,
out of 158 nasal swabs collected from MVC out-patient unit and screened for the
same MTC, 8 (5.1%) were excreting MTC organisms in nasal secretions.
A total of 388 carcasses were inspected for visible lesions (VL) in-situ and
tissue samples from lungs, bronchial lymph nodes, spleen and heart with or
without VL were also collected for further analysis. Of all carcasses and/or organs
inspected, VLs were observed in 22 (5.7%) organs. Tissue impression smears
from organs with or without VLs were stained using Ziehl-Neelsen stain and acidfast
bacilli were observed in 23 (5.9%). The same tissue samples were further
analyzed by PCR using IS6110 primer. Of 388, PCR detected 43 tissue samples
(11.1%) positive for MTC.
The presence of visible lesions and detection of AFB in tissues impression
smears using ZN staining technique has been compared and a statistically highly
significant difference (P
 
Date 2016-05-23T14:57:35Z
2016-05-23T14:57:35Z
2012
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/66230
 
Language en
 
Format application/pdf
 
Publisher Tamil Nadu Veterinary and Animal Sciences University