Bayesian estimation of ELISA and gamma interferon test accuracy for the detection of bovine tuberculosis in caudal fold test-negative dairy cattle in Kuwait

Bovine tuberculosis (TB) is endemic in Kuwait; cattle identified as TB-positive using the caudal fold test (CFT) are culled. We used a Bayesian approach to estimate the sensitivity (Se) and specificity (Sp) of the IFN assay and ELISA, which are not routinely used in Kuwait in CFT-negative dairy cattle. Blood samples from CFT-negative cattle (n = 384) collected from 38 dairy farms were tested by IFN assay and ELISA. The Se and Sp (95% CI) of the IFN were 85.0% (67.6-95.3%) and 90.4% (86.7-95.3%), respectively, whereas estimates for the ELISA were 61.1% (33.1-84.6%) and 85.4% (81.7-88.8%). TB prevalence (95 CI%) in CFT-negative cattle was estimated as 2.6% (0.5-9.5%). The IFN assay may play a role as an ancillary test for the identification of Mycobacterium bovis-infected cattle that are undetected by CFT.