Proceedings of the 10th International Colloquium on Paratuberculosis

#201 Prevalence and distribution <strong>of</strong> paratuberculosis (Johne’s Disease) in cattle herds in Ireland
Margaret Good, Tracy Clegg, Hazel Sheridan, Dermot Yearsley, Tony O’Brien, John Egan, Peter Mullowney
Dept Agriculture, Fisheries and Food, Ireland; Centre for Veterinary Epidemiology and Risk Analysis, University
College Dublin, Ireland
A simple random survey was conducted in Ireland during 2005 to estimate <strong>the</strong> seroprevalence <strong>of</strong> paratuberculosis,
commonly called Johne’s disease (JD), in <strong>the</strong> cattle population. Serum samples were collected from all
20,322 females/breeding bulls over twelve months <strong>of</strong> age in 639 herds (0.7% <strong>of</strong> breeding herds). All samples
were tested using a commercially available absorbed ELISA. The overall prevalence <strong>of</strong> seropositive herds was
21.4% (95% CI = 18.4%, 24.9%). Herd prevalence levels amongst dairy herds (mean 31.5%; CI 24.6%-39.3%)
was higher than among beef herds (mean 17.9 %; CI 14.6%-21.8%). However, <strong>the</strong> animal level prevalence
was similar. The majority <strong>of</strong> herds had only one seropositve animal. Only 6.4% (95% CI 4.7%-8.7%) <strong>of</strong> all
herds had more than one seropositive animal; 13.3% (CI 8.7%-19.7%) <strong>of</strong> dairy herds ranging from two to eight
seropositive animals and 3.9% beef herds (CI 2.4%-6.2%) ranging from two to five seropositive animals. The
true prevalence <strong>of</strong> herds infected and shedding Mycobacterium avium subspecies paratuberculosis is estimated
to be 9.51% for all herd types; 20.63% for dairy herds and 7.58% for beef herds based on a test specificity
<strong>of</strong> 99.8% and test sensitivity (i.e. ability to detect culture-positive animals shedding at any level) <strong>of</strong> 27.8-28.9%.
#216 Calf shedding <strong>of</strong> MAP on two farms with high and low environmental exposure
Rebecca Mans Mitchell, Robert H Whitlock, Julie M Smith, Michael Wood, Nicole S Gollnick, Ynte H Schukken
College <strong>of</strong> Veterinary Medicine, Cornell University, USA; New Bolton Center, University <strong>of</strong> Pennsylvania, USA;
University <strong>of</strong> Vermont, USA; Vermont Agency <strong>of</strong> Agriculture, Food and Markets, USA; Clinic for Ruminants,
University <strong>of</strong> Munich, Germany
Two cohorts <strong>of</strong> calves were followed for 11 months by monthly fecal culture on two nor<strong>the</strong>astern USA dairy
farms with known MAP prevalence. Index calves were selected from dams classified as moderate or high
shedders based on fecal culture. The remainder <strong>of</strong> <strong>the</strong> cohort was selected to be most likely to be raised in <strong>the</strong>
same environment as <strong>the</strong> index animal.
On both farms, fecal samples were collected monthly and stored until completion <strong>of</strong> <strong>the</strong> study. Samples
were batch processed to decrease variability between timepoints. Samples were evaluated at New Bolton
Center by Tetracore’s Vet-AlertTM real-time PCR and fecal culture <strong>of</strong> those samples with positive PCRs.
On farm A, no positive samples from animals were identified including <strong>the</strong> index animal. On farm B, 4
animals in <strong>the</strong> cohort had positive (Ct≤42) or suspicious (Ct> 42) PCRs (a total <strong>of</strong> 7 potential positive samples
were identified out <strong>of</strong> 146). The index animal was negative for all cultures.
Calves in farm B were housed in <strong>the</strong> same barns as <strong>the</strong> milking herd for 6 months before transitioning
to heifer barns. Environmental samples were ga<strong>the</strong>red from within calf pens and <strong>the</strong> contiguous milking herd
pens to evaluate <strong>the</strong> likelihood <strong>of</strong> post-birth exposure. Environmental samples were positive by RT-PCR at 8
<strong>of</strong> 11 sampling timepoints, and for 4 <strong>of</strong> <strong>the</strong> 6 timepoints in which calves were housed exclusively with o<strong>the</strong>r
calves.
Although this analysis did not reveal positive cultures from <strong>the</strong> index animal, on farm B <strong>the</strong>re were multiple
potentially positive calves in <strong>the</strong> cohort, one <strong>of</strong> which cultured positive 3 times in <strong>the</strong> course <strong>of</strong> 4 months. While
we cannot illustrate calf-to-calf transmission, we do see culture positive young animals, even when housed in
an environment which should not involve substantial exposure from adult animals.
190