Sequential Mycobacterium avium subspecies paratuberculosis serology (SMAPS) was recently proposed by Böttcher and Gangl (2004). Briefly, sera are screened in a test of higher sensitivity (Svanovir, Uppsala). Positive sera are tested in both of two tests of higher specificity (Idexx, Wörrstadt; Pourquier, Montpellier). Individual sera are recorded "+++" to "neg", this classification is based on agreement of results and probability of MAP-infection should decrease. The highest serological score per herd defines the herd level (e.g."+++"→A; "neg"→E). Validation of SMAPS was the objective of the present study.Totally 7502 blood samples and 1829 faecal samples (937 animals) were collected from 113 herds. In order to increase sensitivity of bacterial culture and to analyse serological differences over time up to three faecal/blood samples were collected per cow, respectively.MAP was detected in 23 (2.4%) of 937 tested animals. Positive bacterial culture was significantly associated with "+++"-seroreactivity (48%). MAP was isolated in 2.7%, 1.8%, 0.8% and 1.0% of "++", "+", "(+)" and "neg" animals, respectively. However, it has to be stressed that bacterial culture was positive only in "A"-herds. In none of the herds of other classes ("B" to "E") a positive result in culture was obtained. SMAPS is a valuable tool for detection of high risk herds ("A"). Further SMAPS pinpoints additional infected animals in those high risk herds. Stability of serological results over time remains to be analysed.

References

Böttcher, J. and A. Gangl: Mycobacterium avium ssp. paratuberculosis - combined serological testing and classification of individual animals and herds, 2004; J. Vet. Med. B 51, 443-448