Summary10 Icp


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An Overview of presentations at 10th International Symposium on Paratuberculosis

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Summary10 Icp

  1. 1. Interesting snippets from the 2 nd Paratb forum August 8 th 2009 & 10 th International Colloquium on Paratuberculosis 9-14 Aug 2009 Margaret Good SSVI Peter Mullowney SVI
  2. 2. Mike Collins
  3. 5. Reasons to Cull ELISA Strong-Positive Cows <ul><li>Likely to go clinical next lactation </li></ul><ul><li>Likely not to complete a full lactation </li></ul><ul><li>Decreased production next lactation </li></ul><ul><li>Likely carrying an infected fetus if PG </li></ul><ul><li>Heavy shedders = highly infectious </li></ul><ul><li>Will contaminate maternity pen causing more infected heifers </li></ul>
  4. 6. Susceptibility to MAP <ul><li>Windsor and Whittington, 2099, Vet J </li></ul><ul><li>Young calves (<6 mos) less resistant to infection than older cattle </li></ul><ul><li>Older cattle can become infected </li></ul><ul><ul><li>Brian Kirkpatrick presented on a Whole genome association study for Holstein susceptibility to MAP infection </li></ul></ul><ul><ul><li>Possible SNP associations with paratuberculosis susceptibility identified in multiple locations </li></ul></ul>Scott Wells University of Minnesota presented on Age related susceptibility 19% 18% 57 >12 mos 50% 38% 26 6-12 mos 74% 47% 57 <6 mos % Lesions % Clinical JD No cattle Age
  5. 7. M. Paratuberculosis common in environment surrounding dairy farms <ul><li>In Austria J. Khol </li></ul><ul><li>Assigned correct status to 70% herds by environmental sampling & culture. </li></ul><ul><li>3 consecutive samples 80% of herds assigned correct status. </li></ul><ul><li>All herds with high within herd prevalence detected. </li></ul><ul><li>Accurate & economic screening method </li></ul><ul><li>Minnesota dairy farms </li></ul><ul><li>(Raizman et al., JDS,2004) </li></ul><ul><ul><li>Positive cow alleyways on 77% of infected farms </li></ul></ul><ul><ul><li>Manure storage on 68% of infected farms </li></ul></ul><ul><li>US dairy farms (USDA-APHIS-VS NAHMS Dairy 2007) </li></ul><ul><ul><li>68% of herds test-positive. Cow level prevalence 4.8% with 18.8% of those heavy shedders </li></ul></ul><ul><ul><li>Pooled environmental samples positive if at least one heavy shedder </li></ul></ul><ul><ul><li>Most cost effective for medium sized herds <10% prevalence was pooled faecal culture 10 or 5/pool. </li></ul></ul><ul><li>Cornell univ. Checked suspect ‘pass through’ and found most were confirmed infected in tissue samples (low shedders may be infected by super-shedders as they did share strains) </li></ul><ul><li>Maarten Weber </li></ul><ul><li>(GD The Netherlands) </li></ul><ul><li>Compared slurry pit (91% +ve) & cow alley (87% +ve) culture in 222 known +ve herds with at least 1 culture +ve cow. </li></ul><ul><li>5-13% herds false negative. </li></ul>
  6. 8. Sampling cow alleys!! (Ian Gardner)
  7. 9. Rebecca Mitchell did a meta-analysis of calves and Map <ul><li>Historically calves not considered an important source of MAP </li></ul><ul><li>Experimental infection data indicates calves often have an infectious period. </li></ul><ul><li>Mathematical models would suggest that challenge dose dependent shedding may result in self-propelling endemicity (backward bifurcation) </li></ul><ul><li>17 studies Published between 1953 and 2007 Total of 197 animals </li></ul><ul><li>Found </li></ul><ul><li>Experimentally infected calves shed in 2 phases – early, followed by a carrier non shedding period then a late shedding phase </li></ul><ul><li>Strong relationship between dose and duration of early shedding is sufficient to allow backward bifurcation ( an increase in effective reproduction ratio relative to basic reproduction ratio once prevalence reaches a specific threshold) </li></ul><ul><li>Endemic infection can be sustained at reproduction ratios which would not support introduction. </li></ul>
  8. 10. Vangenugten looked at birth clusters of Map <ul><li>Confirmed: Calves from test-negative dam that were born within 10 days following the calving of a shedding dam were 5 times more likely to become a MAP shedder later in life compared to calves that were not exposed. (Benedictus et al. 2007) </li></ul><ul><li>Birth clusters appear to be present and contribute a large proportion of incident cases of MAP to a dairy farm operation: </li></ul><ul><ul><li>10 day cluster most prevalent (calving pen?) (pooled colostrum?) </li></ul></ul><ul><ul><li>60,90,120 clusters also observed (calf-to-calf?) </li></ul></ul><ul><li>MAP control program with an emphasis on calving pens and a test-and-cull program virtually eliminate birth clusters. </li></ul>
  9. 11. <ul><li>Perez took illeo-caecal valves of 15,546 extensively reared calves 8-12mths old slaughtered out of 137 herds in Spain. </li></ul><ul><li>Microscopic examination for lesions and acid fast organisms (ZN) (PCR confirmatory on a sample of +ves) </li></ul><ul><li>Demonstrated the method as efficient in detecting lesions in sub-clinical animals </li></ul><ul><li>Lesions in 444 calves 2.83% and if herds with at least one detection were considered positive 49.63% herds are positive </li></ul>
  10. 12. Off-site rearing of dairy heifers to reduce Johne’s disease risk (Ian Gardiner) 257/638 (40.3) 148/797 (18.6) 10/461 (2.2) 2.3 638 OFF/OFF Reared offsite 292/581 (50.3) 210/791 (26.5) 16/365 (4.4) 3.6 581 ON/OFF Off inf farm at 5 months 319/601 (53.8) 194/797 (24.3) 18/307 (5.9) 4.6 601 ON (reared on infected farm) First 3 lactations (%) Birth to first calving (%) Positive (%) herd test Positive (%) lacs 1 and 2 No. first lactation Cohort Mortality and Culling ELISA positive
  11. 13. Jason Lombard presented on the results of the JD herd management Project began in 2003 <ul><li>Primary Objective </li></ul><ul><ul><li>Evaluate effect of long-term management on control of JD </li></ul></ul><ul><li>Status (2009): </li></ul><ul><ul><li>Seventh and final year of study </li></ul></ul><ul><ul><li>17 States have enrolled herds </li></ul></ul><ul><ul><li>66 dairy herds (~175,000 animals) – 16 States </li></ul></ul><ul><ul><li>23 beef herds (~30,000 animals) – 11 States </li></ul></ul>
  12. 15. Similarly Preliminary Results presented by Sorge on the Canadian voluntary JD risk assessment control programme showed a within herd fall in prevalence <ul><li>** based on JD milk ELISA test positive or suspect cows </li></ul><ul><li>Maximum apparent within-herd prevalence (n=159) </li></ul><ul><li>In 2005/07: 42%. In 2008/09 18.9% </li></ul>1.6 2.0 Lactation ≥3 1.4 1.6 Lactation2 0.7 0.8 Lactation 1 1.6 ± 3.0 2.4 ±4.9 Within-Herd Prevalence** 2 nd Test (08/09) 1 st Test (05/07) Apparent Prevalence Based on 159/240 herds
  13. 16. Preliminary Results <ul><li>Herds with individual calving stalls have a lower prevalence (1.4%) than those without (3.6%) (p=0.022) </li></ul><ul><li>The more cows that were calving together, the higher the prevalence of JD test-positive cows at the 2 nd test (p=0.042) </li></ul><ul><li>The prevalence dropped MORE in herds using individual cow maternity pens (-1.2%) than in herds not using individual calving pens (+0.2%) (p=0.042) </li></ul><ul><li>Poor Hygiene throughout the farm (i.e., all age groups) was associated with higher prevalence </li></ul><ul><li>Purchase of cows in last 10 years before ’05-’07 was associated with increased JD prevalence in ’08-’09 (p<0.05) </li></ul>-Preliminary Results-
  14. 17. Trier presented on a Danish co-op with an ‘experience’ group of farmers as part of the JD control <ul><li>Experience Group </li></ul><ul><li>8 groups of geographically based farmers </li></ul><ul><li>The co-op rep., a Facilitator and the Local advisor (veterinarian or other) </li></ul><ul><li>Meet Twice a year on a different farm of one participant each time </li></ul><ul><li>The farmer shows the farm and tells how he attempts to control MAP </li></ul><ul><li>Participants provide feedback and make suggestions for alternatives </li></ul>
  15. 18. <ul><li>The facilitator </li></ul><ul><ul><li>Ensures all major risk areas are discussed </li></ul></ul><ul><ul><li>Summarize the advice given by the group members </li></ul></ul><ul><ul><li>Brings new knowledge </li></ul></ul><ul><ul><li>Encourage the farmers </li></ul></ul><ul><li>Valuable to the Co-op </li></ul><ul><ul><li>Feedback from the farmer </li></ul></ul><ul><ul><li>Areas that need focus </li></ul></ul><ul><ul><li>Where are the obstacles? </li></ul></ul><ul><ul><li>Demonstrate success in controlling MAP </li></ul></ul><ul><li>Valuable to the farmer </li></ul><ul><ul><li>Focus </li></ul></ul><ul><ul><li>Helps to find solutions </li></ul></ul><ul><ul><li>Gives ideas </li></ul></ul><ul><ul><li>High motivation </li></ul></ul><ul><ul><li>Education </li></ul></ul><ul><ul><li>Engage the advisers </li></ul></ul><ul><ul><li>Commitment to the group </li></ul></ul><ul><li>Conclusion </li></ul><ul><li>Improved routines </li></ul><ul><li>The quality of the discussions has improved </li></ul><ul><li>The knowledge of infection protection has improved </li></ul><ul><li>Meetings are valuable to the farmers </li></ul>
  16. 19. <ul><li>Kruze (Chile) demonstrated a lag time of two months from spreading slurry contaminated by map and finding of map in water samples. </li></ul><ul><li>Map leaching favoured by light soil textures and increasing rainfall </li></ul><ul><li>Dhand (Australia) suggest that under experimental conditions that Map adsorbs to a range of soil particles influenced by soil pH. </li></ul>
  17. 20. Phage based detection of Map Univ. Nottingham and Vet service Cyprus <ul><li>Used fast plaque TB from biotech normally used for sptutum sampling in humans </li></ul><ul><li>No decontamination steps therefore no loss of organisms (VISAVET said decontamination reduces colony counts by 2.5log) </li></ul><ul><li>Milk samples TBC indicated Map detected in non-clinical cows was not a result of faecal contamination </li></ul><ul><li>Phase based test more sensitive than culture </li></ul><ul><li>UK – 54 samples; 19(35.2%) phage +ve only 1% PCR and none culture </li></ul><ul><li>Cyprus – 225 samples; 218 +ve phage, 50 PCR, 2 culture </li></ul><ul><li>Phage also detects M. bovis in milk </li></ul>
  18. 22. Conclusions <ul><li>Map was detected and cultured from diaphragm muscle of paratuberculosis infected cattle destined for human consumption </li></ul><ul><li>In general there was a positive association between the severity of the enteric lesions, clinical signs of paratuberculosis, heavy bacterial load in intestinal tissues, fecal shedding of Map and the presence of disseminated Map infection in diaphragm muscle. </li></ul><ul><li>Two of the positive animals did not show clinical signs associated to paratuberculosis and one was not confirmed as fecal shedder, suggesting that meat from both symptomatic and asymptomatic animals could potentially represent a source of exposure to Map to humans. </li></ul>