Experience with the Danish Mix-ELISA in the United States
This article details some of our experiences with Danish mix-ELISA (DME) testing on herds in the United States. In contrast to Denmark, clinical outbreaks of Salmonella Choleraesuis occur in the United States. We examine the appropriateness of the current cut-off of OD%>=40 for U.S. herds by examining serum and fecal samples collected from individual pigs and tested with the DME and culture, respectively. We report the estimated sensitivity and specificity of the DME using the original and possibly modified cut-off values. The 30% cutoff was deemed optimal with a sensitivity of .57 (.45, .82) and a specificity of .84 (.68, .98) for the first set of samples and .69 (.49, .93) and .63 (.53, .76) for the second set of samples. A major use of these tests is for monitoring herds for Salmonella exposure over time. Information on the sensitivity and specificity of the DME is helpful in determining how many animals in a herd to sample and how often.