Proceedings of the 10th International Colloquium on Paratuberculosis

Herd prevalence
District Herds tested (N) ELISA positive HAP % HTP %
Vt1 10 5 50 36.11
Vt2 10 3 30 -53.0
Vt3 10 6 60 72.5
Vt4 10 4 40 9.4
Vt5 10 2 20 -13.07
Total 50 20 40 13.1
The assessment <strong>of</strong> prevalence obtained should be comparable to o<strong>the</strong>r studies and might be
important to plan prospective studies or to make rational health planning decision.
REFERENCES
Nielsen SS, T<strong>of</strong>t N, 2009. A review <strong>of</strong> prevalences <strong>of</strong> paratuberculosis in farmed animals
in Europe. Prev Vet Med, 88, 1-14.
Rogan WJ, Gladen B, 1978. Estimating prevalence from <strong>the</strong> results <strong>of</strong> a
screening test.Am J Epidemiol, 107: 71-76.
#139 Prevalence <strong>of</strong> Mycobacterium avium subsp. paratuberculosis infection in adult Danish
non-dairy cattle sampled at slaughter
Hisako Okura, Søren Saxmose Nielsen, Nils T<strong>of</strong>t, University <strong>of</strong> Copenhagen, Denmark
A voluntary, risk-based control program for paratuberculosis in dairy herds was started in 2006 in Denmark.
The program does not include non-dairy herds, and <strong>the</strong> occurrence <strong>of</strong> Mycobacterium avium subsp. paratuberculosis
(MAP) in <strong>the</strong>se herds is unknown. The objective <strong>of</strong> this study was to establish <strong>the</strong> prevalence <strong>of</strong> MAP
infected adult non-dairy cattle in Denmark.
Serum samples were collected between October, 2008 and January, 2009 from every 6th animal over
24 months <strong>of</strong> age, sent to slaughter to Danish slaughterhouses from non-dairy herds. The sample included
2,368 cattle, <strong>the</strong> largest breed was crossbred (<strong>of</strong> unknown breeds) (30%) and <strong>the</strong> three dairy breeds (Holstein,
Jersey and Danish Red Cattle) comprised 27% <strong>of</strong> <strong>the</strong> cattle. The serum samples were tested using an antibody
ELISA (IDScreen ® kit from ID-Vet) and positives were defined as <strong>the</strong> sample-to-positive ratio greater than 0.60.
Information about test sensitivity (Se) and specificity (Sp) were based on literature data. Se was set for each
year-age-group from 0.2 (95th percentile: 0.30) to 0.5 (95th percentile: 0.60) for 2-3 year-age-group and older
than 5 year-age-group, respectively. Sp was set to 0.995 (5th percentile: 0.90) regardless <strong>of</strong> <strong>the</strong> year-age-group.
Using <strong>the</strong> test information, estimation <strong>of</strong> <strong>the</strong> true prevalence (TP) (stratified by breed) was done in a
Bayesian analysis (with a random effect <strong>of</strong> breed) using WinBugs s<strong>of</strong>tware. Overall, <strong>the</strong> estimated TP was
0.01 (95% CPI: 2.7E-6 - 0.06), with large differences between breeds. The dairy breeds Jersey, Holstein and
Danish Red Cattle had highest ranked TP (mean: 0.13, 0.10, and 0.06, respectively). The former two were <strong>the</strong>
only breeds significantly different from <strong>the</strong> population mean. The results needs to be fur<strong>the</strong>r scrutinized, but <strong>the</strong>
indication <strong>of</strong> dairy-breeds having a higher prevalence might provide a starting point for fur<strong>the</strong>r analyses into <strong>the</strong>
potential causes <strong>of</strong> this difference.
182