The interpretation of serial Johne’s disease milk antibody results is affected by test characteristics, pattern of test results and parallel bovine tuberculosis testing

The Occurrence of Mycobacterium avium Subspecies paratuberculosis Positive Milk Antibody ELISA Results in Dairy Cattle under Varying Time Periods after Skin Testing for Bovine Tuberculosis

“…The Poisson regression results, however, do suggest that there is a diagnostic benefit in not JD testing too closely to the previous bTB test. This is in line with the observations of May et al and Barden et al [ 22 , 24 ]. The findings of the current study further clarify the effect of bTB–JD testing intervals: for ‘medium’ risk cows, the largest increase in probability of a positive JD test is with testing interval categories of 29–42 days (OR = 2.4) and 43–56 days (OR = 2.6).…”

“…The findings of the current study further clarify the effect of bTB–JD testing intervals: for ‘medium’ risk cows, the largest increase in probability of a positive JD test is with testing interval categories of 29–42 days (OR = 2.4) and 43–56 days (OR = 2.6). This is very similar to the findings of May et al, whilst Barden et al reported an earlier (0–30 days post-bTB test) rise in odds for testing positive for JD [ 22 , 24 ]. The ‘high’ risk cows are more likely to be identified in the bTB–JD testing interval categories 43–56 and 57–70 days (OR = 3.2 and 4.0, respectively).…”

“…Q–Q plots and normality of residuals were used to evaluate the models. In order to evaluate whether the bTB–JD testing interval was affected by an occurrence of a short (<60 day) testing interval, coded events of pre- and post-intervals were introduced to the final mixed linear model [ 24 ]. Finally, in case repeat events of a short bTB–JD testing interval occurred, these were coded and put in the final mixed linear model to enable evaluation of whether a repeat event had a different bTB–JD testing interval.…”

“…They therefore recommended postponing MAP milk ELISA testing for 43 days and MAP serum ELISA testing for 71 days post-SICCT. Similarly, Barden et al showed an increased rate of a positive JD test result up to 30 days (odds ratio (OR) = 2.08) and 31–60 days (OR = 1.15) after bTB testing [ 24 ].…”

SVEPM 2020 — Resilience and community support in the first year of the COVID-19 pandemic: The Society for Veterinary Epidemiology and Preventive Medicine Annual Conference, extraordinarily held online

“…Testing and culling was shown to be particularly effective when used prior to the calving season. Acknowledging the key role of testing in planning control strategies, Barden et al (2020) used Bayesian statistics to study milk antibody ELISA tests and calculate the probability of infection under various circumstances. The authors demonstrated a reduction in test specificity associated with parallel bovine tuberculosis testing, highlighting the complex management and health settings which can affect test interpretation, and under which control decisions must be made.…”