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

Abstract

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 IFNγ 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 IFNγ assay and ELISA. The Se and Sp (95% CI) of the IFNγ 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 IFNγ assay may play a role as an ancillary test for the identification of Mycobacterium bovis–infected cattle that are undetected by CFT.