G. Ameni et al., Comparison between comparative tuberculin and gamma-interferon tests for the diagnosis of bovine tuberculosis in Ethiopia, TROP ANIM, 32(5), 2000, pp. 267-276
A study to determine and compare the sensitivities and specificities of the
comparative cervical tuberculin (CCT) and gamma-interferon (IFN-gamma) tes
ts for the diagnosis of bovine tuberculosis was conducted on 30 zebu oxen.
The results of the tests were compared with the presence of acid-fast bacil
li found by bacteriological culturing and histopathological examinations. T
he sensitivity and specificity of CCT test were found to be 90.9% and 100%,
respectively. Those of the commercial IFN-gamma test were determined to be
95.5% and 87.7%, respectively. No significant differences were found betwe
en the sensitivities (Yates' corrected chi(2) = 0.32; p = 0.57) or the spec
ificities (Yates' corrected chi(2) = 2.54; p = 0.11) of the two tests. Furt
hermore, a positive correlation (r = 0.76) was recorded between the increas
e in skin thickness following injection of bovine purified protein derivati
ve (PPD) and the optical density in the gamma-interferon assay with bovine
PPD. On the other hand, the correlation (r = 0.47) between the change in sk
in thickness following injection of avian PPD and the optical density in th
e gamma-interferon assay with avian PPD was relatively weak. On the basis o
f this preliminary investigation, it was concluded that the choice between
the two tests depends on their cost and simplicity and on livestock managem
ent and time factors rather than on their respective diagnostic value.