Table 1.

Explanation of the terminology used in this review

Term	Explanation
Gold standard	A perfect definitive test that produces no misclassifications
Sensitivity	Probability of a positive test result given the animal is truly infected
Specificity	Probability of a negative test result given the animal is truly not infected
Titre	The highest dilution of the sample at which the test is still positive
Optical density (OD)	Colour (absorbance) change in a sample resulting from the conversion of substrate and measured using spectrophotometry
Cut-off OD value	The absorbance above which samples are considered positive
Receiver operator characteristic	Statistical method used to calculate cut-off OD values
Sample to positive (SP) ratio or Optical density ratio (ODR)	The ratio of the OD of the sample to the OD of the positive control (SP ratio = ODsample/ODpositive control)
Percent positivity (PP)	Sample to positive ratio x100