Comparison of an indirect ELISA in blood serum versus, an indirect milk ELISA for diagnosis of paratuberculosis in dairy cattle

Performed in the province of Buenos Aires, Argentina

Abstract

The aim of this paper was to compare the operational characteristics of serum ELISA with milk ELISA, for the diagnosis of bovine paratuberculosis. Using ROC analysis, the area under the curves were 0.84 in serum ELISA and 0.88 in milk ELISA, without significant differences (p= 0.30) between both AUC; the sensitivities were 91.7% and 87.5%, the specificities 82.0% and 86.5% for serum ELISA and milk ELISA respectively. In addition, days in lactation and lactation numbers were also included as variables. Days in lactation were analyzed with correlation and simple linear regression, showing a positive relationship (p < 0.05) between serum ELISA and milk ELISA. Lactations numbers were analyzed only in milk ELISA with ANOVA, significant differences (p= 0.016) were evident between 1st groups with 2nd and> 2nd lactations. The preliminary results demonstrate that serum ELISA presents similar operational characteristics to milk ELISA, being milk ELISA a practical and less invasive alternative to sampling.