Comparison of Milk and Serum Enzyme–Linked Immunosorbent Assays for Diagnosis ofMycobacterium AviumSubspeciesParatuberculosisInfection in Dairy Cattle

Abstract

Abstract. Milk and serum samples from 35 dairy herds in 17 states were evaluated for cow-and herd-level Mycobacterium avium subspecies paratuberculosis (MAP) antibody test agreement. Evaluation of 6,349 samples suggested moderate agreement between milk and serum enzyme-linked immunosorbent assay (ELISA) results, with a kappa value of 0.50. Cow-level sensitivity (Se) for 18 dairy operations with 1,921 animals was evaluated relative to fecal culture results. At the cow level, the milk ELISA relative Se was not significantly different from that of the serum ELISA (21.2 and 23.5%, respectively). Logistic regression models revealed a positive association between lactation number and milk ELISA status. Non-Holstein cows were more likely to test milk ELISA positive than Holstein cows. Cows in the first 2 weeks of lactation and after week 45 of lactation were more likely to test milk ELISA positive than cows between 3 and 12 weeks of lactation. Milk production . 80% of herd average was negatively associated with testing milk ELISA positive. Animals in the West and Midwest regions were less likely than animals in the Southeast region to test ELISA positive by either test. Estimates for herd-level sensitivity for the milk and serum ELISA, relative to fecal culture results, ranged from 56 to 83%. At the cow and herd levels, milk ELISA performed equivalent to serum ELISA using fecal culture as a reference for MAP infection and has the advantage of decreased labor costs on farms that use Dairy Herd Improvement Association testing.

A longitudinal study of factors influencing the result of a Mycobacterium avium ssp. paratuberculosis antibody ELISA in milk of dairy cows

“…Hence, several authors have recommended taking milk yield and parity factors into account when interpreting milk ELISA results instead of using a standard cutoff value (Nielsen et al, 2002b;Sanchez et al, 2004;Lombard et al, 2006;Norton et al, 2010;Nielsen and Toft, 2012). The data presented in our study clearly support the notion that intrinsic milk factors, as well as individual cow factors, influence specific MAP milk ELISA test results and endorse the assumption that total IgG concentration in milk is influenced in a similar way.…”

“…There is increasing evidence for the influence of milk yield or lactation stage on the outcome of the MAP diagnosis by milk ELISA (Nielsen et al, 2002a,b;Lombard et al, 2006;Nielsen and Toft, 2012). Hence, several authors have recommended taking milk yield and parity factors into account when interpreting milk ELISA results instead of using a standard cutoff value (Nielsen et al, 2002b;Sanchez et al, 2004;Lombard et al, 2006;Norton et al, 2010;Nielsen and Toft, 2012).…”

“…A similar characteristic holds true for antibodies against MAP, with the odds of detecting MAP antibodies being 130 times higher at 0 DIM as compared with 4 DIM (Zervens et al, 2013). Furthermore, milk yield was shown to be negatively associated with milk ELISA outcome for MAP but also for Ostertagia ostertagi (Sanchez et al, 2004;Lombard et al, 2006;Nielsen and Toft, 2012). Therefore, it was recommended to include milk yield in the interpretation of ELISA results to enhance its diagnostic value (Sanchez et al, 2004;Nielsen and Toft, 2012).…”

“…A fecal PCR can be performed and, although it is much faster, it faces similar limitations as the fecal culture (Sweeney, 2011). Progression of disease from asymptomatic to clinical is positively associated with an increase of the humeral immune response; therefore, the milk ELISA has been described as a useful tool to identify infectious animals (Chiodini, 1996;Lombard et al, 2006;Nielsen, 2008). As the interpretation of the ELISA is based on a cutoff value, it is important to know what other factors besides disease status influence the test result.…”

Management Practices and Their Potential Influence on Johne’s Disease Transmission on Canadian Organic Dairy Farms—A Conceptual Analysis

“…In Canada, Channel Islands breeds (e.g., Jersey, Guernsey) have been shown to have increased odds of being JD ELISA positive [72]. Lombard et al [98] showed that non-Holstein breeds are more likely to test positive using serum or milk ELISA. Therefore, when trading with or breeding those breeds, organic farmers may be more likely to introduce and spread JD on their farm.…”