We report on the diagnostic sensitivity of 3 EU-approved rapid tests (1 from IDEXX and 2 from BIO-RAD) for the detection of transmissible spongiform encephalopathy (TSE) diseases in goats. Ninety-eight goat brain stem samples were tested. All of rapid tests had 100% specificity and ≥80% sensitivity with the IDEXX test significantly more sensitive than the 2 Bio-Rad tests. All tests detected 100% of samples from goats with clinical scrapie, but missed between 7% (IDEXX) and 24% (BIORAD-SG) of samples from pre-clinical goats. Importantly, only IDEXX picked up all samples from clinical BSE-infected goats, whereas the other 2 rapid tests missed between 15% (BIORAD-SG) and 25% (BIORAD-SAP). These results show that a fraction of pre-clinical scrapie infections are likely missed by the EU surveillance, with sensitivity of detection strongly depending on the choice of the rapid test. Moreover, a significant proportion of clinical BSE infections are underestimated by using either BIO-RAD test. Assuming that the same sensitivity on pre-clinical goats would also occur in BSE-infected goats, our data suggest that IDEXX is likely the most sensitive test for detecting preclinical field cases of BSE infection in goats, though with a 7% failure rate. These results raise some concerns about the reliability of current EU surveillance figures on BSE infection in goats.
- rapid tests