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

Abstract

Enzyme-linked immunosorbent assays (ELISA) are used to screen cows for Mycobacterium avium subspecies paratuberculosis (MAP) infections, informing Johne’s disease (JD) management practices in dairy herds. The causative agent of bovine tuberculosis (bTB), Mycobacterium bovis, and MAP share multiple antigens. Moreover, Mycobacterium avium subspecies avium is used in the single intradermal cervical comparative tests (SICCT) that are routinely used in early detection of cows infected with bTB. Although these are different types of immune responses, potentially the SICCT may interfere with the levels of MAP antibodies. This study aimed to clarify the relationship between the SICCT-MAP milk ELISA testing interval and apparent prevalence of JD risk statuses. Data from 51 herds were used, totalling 46,738 cow observations. The Poisson models showed that MAP milk ELISA testing at 14 day intervals post-SICCT statistically significantly increased the odds of detecting JD-positive cows compared to JD testing 85+ days post-SICCT. The odds ratio (OR) started at 2.5 in the first 14 day interval post-SICCT, increasing each two-week period to an OR of 4.0 at 57–70 days, to subsequently drop. Additionally, a herd history of bTB increased the odds of detecting JD-positive cows (OR = 1.2); this was relatively limited compared to the magnitude of the post-SICCT effect.

Effect of tuberculin skin testing on serological results against Mycobacterium avium ssp. paratuberculosis (MAP): Evidence of distinct effects in MAP-infected and noninfected cows

“…A recent study performed by Barden et al (2020) showed an increase in the odds of a positive MAP test result when MAP milk ELISA testing occurs less than 30 d to SICCT testing. A similar result was also found by Bridges and van Winden (2021), who reported an increased risk of testing positive in the MAP milk ELISA, with a gradually increasing risk, peaking 57 to 70 d post SICCT testing to subsequently wain. In this study, we aim to further characterize the relationship between SICCT testing and MAP milk ELISA performance, including an assessment of whether the immunological response to the SICCT test is different for MAP-infected cows and noninfected cows.…”

Evaluation of the diagnostic accuracy of the serological test for paratuberculosis in cattle according to tuberculosis status

“…31 Monitoring the humoral immune response by bPTB-ELISA provides faster results and is a cheaper alternative to other diagnostic tools to detect infected animals. 8,10 However, different studies have questioned the usefulness of the technique due to its limited accuracy, 10,12,15,32,33 which should be considered when designing a bPTB control programme. 1,7 Different studies showed that the SE and SP values of the bPTB-ELISA ranged between 7% and 94% and 40% and 100%, respectively, 8,12 depending on the test, the sample used in the reference test (faeces or intestinal tissues), age or clinical stage of infection, 8,11 interference with other mycobacteria [14][15][16] or the time elapsed between the test and the SIT test.…”

“…1,7 Different studies showed that the SE and SP values of the bPTB-ELISA ranged between 7% and 94% and 40% and 100%, respectively, 8,12 depending on the test, the sample used in the reference test (faeces or intestinal tissues), age or clinical stage of infection, 8,11 interference with other mycobacteria [14][15][16] or the time elapsed between the test and the SIT test. 13,17,32,33 In the present study, microbiological culture of intestinal tissue (ileocaecal lymph nodes and ileocaecal valve, respectively) was used as a reference test, in contrast to most studies using faecal samples. However, tissue culture is more sensitive than faecal culture, allows detection of animals in the early stages of infection, is a postmortem technique to confirm the diagnosis of positive animals 11 and is also used to validate rapid diagnostic tests.…”

The Risk of False-Positive Serological Results for Paratuberculosis in Mycobacterium bovis-Infected Cattle

“…It should be highlighted that in addition to M. bovis- infection, performing a TST can also influence MAP-positive results in tested animals. It is possible that TST could boost the antibody response and increase the sensitivity of paratuberculosis ELISA results [ 10 , 24 ]; this would indicate that at least some of the results were not false positives. However, the limited number of serological studies in Poland have found the seroprevalence of paratuberculosis in cattle to be much lower (1–3%) [ 25 ].…”

“…It is also known that exposure to environmental NTM can reduce the specificity of M. bovis diagnostic tests [ 9 ]. However, only a few studies [ 10 , 11 ] have examined the inverse relationship: the effect of MTBC infection on MAP diagnostic results.…”