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Appendix B USAHA VOLUNTARY JOHNE’S DISEASE HERD STATUS PROGRAM FOR CATTLE United States Animal Health Association 1998 Committee Reports—Johne’s Disease U.S. Voluntary Johne’s Disease Herd Status Program for Cattle Preface Johne’s disease (paratuberculosis) is a growing concern to U.S. cattle industries. Years of research effort have produced several new diagnostic tests to detect Mycobacterium paratuberculosis-infected cattle. These tests have been evaluated independently by several research groups and been found sufficiently accurate to reliably be used in a program to certify cattle herds as having negligible risk of infection. In 1993, a task force of the Johne’s disease committee of USAHA drafted a model Johne’s disease herd certification program (USAHA, 1993). Some states modified their Johne’s disease certification programs to conform to
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this model. However, relatively few herd owners have elected to pursue herd certification citing the amount of testing required and the associated costs as the main deterrent. Consequently, in 1997 the USAHA National Johne’s Working Group (NJWG) appointed a committee to try to design a more affordable and yet scientifically sound herd certification program. Multiple meetings were held to design this program and input was solicited from experts and all stake holders. The program was submitted for discussion at NJWG meetings held in conjunction with the Livestock Conservation Institute’s meeting March 1998 and the National Cattlemen’s Beef Association meeting in July 1998. In August 1998, the program was sent to all state veterinarians, area-veterinarians-in-charge, veterinary associations, cattle breed associations, and interested industry groups for comment. The program was adopted by USAHA in October 1998. The program presented in this document is intended as a model. The guidelines are considered minimal requirements for operation of a scientifically sound program to identify herds of low risk of M. paratuberculosis infection (Johne’s disease). This model program was developed to assist State Veterinarians and Johne’s disease advisory committees, or their equivalent, in each state as they consider implementation of Johne’s disease herd certification programs. It is hoped that the model program will promote greater similarity and equity among different state programs. NJWG Herd Certification Subcommittee members: Leslie Bulaga, Co-chair, USDA/APHIS/Veterinary Services Michael Collins, Co-chair, University of Wisconsin School of Veterinary Medicine Ian Gardner, University of California, School of Veterinary Medicine William Hartmann, Minnesota Board of Animal Health Karen Jordan, National Milk Producers Federation Richard Keene, National Holstein Association Lee McPhail, Ohio Department of Agriculture Ken Olson, American Farm Bureau Federation Boyd Parr, American Farm Bureau Federation William Rotenberger, Steele Veterinary Clinic and Chair USAHA Johne’s Committee Joseph VanTiem, USDA/APHIS/Veterinary Services Gary Weber, National Cattlemen’s and Beef Association Scott Wells, USDA/APHIS/Veterinary Services Robert Whitlock, University of Pennsylvania, College of Veterinary Medicine
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U.S. VOLUNTARY JOHNE’S DISEASE HERD STATUS PROGRAM FOR CATTLE OCTOBER 1998 Definitions Herd: a group of cattle managed as a separate and discrete unit not commingled with other groups of susceptible species. All cattle on two or more premises geographically separated but on which cattle have been interchanged or where there has been contact between the premises is considered one herd. Contact of animals between separated premises under common management is assumed to have occurred unless complete separation and biosecurity measures between premises can be established by the herd owner or manager. Herd member: any susceptible species of animal that is commingled with the herd. Commingling: physical contact or exposure to manure or raw milk of susceptible species. For example, all cattle and other susceptible species grazed together or on the same area of a property or farm, at any time during any 12-month period, are considered to be commingled. Susceptible species include domesticated and exotic ruminants such as sheep, goats, cervids, and camelids. Exposure to manure via contaminated water or feed sources is also considered commingling. Biosecurity: animal husbandry and hygiene practices designed to limit opportunities for exposure to M. paratuberculosis. Animal identification: all cattle in a Program herd must be permanently and individually identified using an identification method approved by the State Johne’s Advisory Committee. However, Level 4 herds must individually identify all cattle using a USDA approved official identification system. Accredited Veterinarian: a veterinarian approved by the Deputy Administrator of USDA/APHIS/VS to perform functions required by State-Federal-Industry cooperative programs. For the Voluntary Johne’s Disease Herd Status Program (VJDHSP) these duties include annual herd visits, animal testing, and producer education. All samples for Program testing must be collected by an accredited veterinarian or State or Federal animal health official. Accredited Laboratory: a laboratory that has passed an annual check test for Johne’s disease administered by the National Veterinary Services Laboratories. All program testing must be conducted by a laboratory approved for the specific test being used. Johne’s Epidemiologist: a State or Federal regulatory health official who has demonstrated the knowledge and ability to perform the functions specified by the VJDHSP. The Johne’s epidemiologist should be selected in consultation with the State Johne’s Advisory Committee, State animal health official, Area-Veterinarian-in-Charge, and the National Program Coordinator. National Program Coordinator: a USDA staff veterinarian who will assist State Johne’s epidemiologists, State Johne’s Advisory Committees, and the
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USAHA Johne’s Committee with the administration and review of the Voluntary Johne’s Disease Herd Status Program. Herd Status Levels: herds may achieve status Levels of 1, 2, 3 or 4. Each level of increase indicates higher confidence in the Johne’s disease free status of the herd. (Percentages shown on the flow diagrams in Appendix II represent a mathematical estimate of the probability herds at each level of certification are free of Johne’s disease based on serial testing.) Level achievement year: the year in which a herd met Program standards to be granted a specific status Level. For example, a herd completing Level 2 testing in 1998 that elects to remain at Level 2 would have Level 2 1998 status. Level achievement year is noted because continued monitoring increases confidence the herd is not infected. ELISA or Fecal Culture Statistical subset: an ELISA on or fecal culture of a statistically determined number of animals. The table in Appendix I shows the number of animals to include in Program ELISA and fecal culture statistical subset testing. State Johne’s Advisory Committee: an appointed committee which is the authority responsible for overseeing and coordinating the State’s Voluntary Johne’s Disease Herd Status program. The Committee may be comprised of any or all of the following: Dairy producers—purebred, commercial and commodity groups Beef producers—purebred, commercial and commodity groups University Extension—beef and dairy Veterinary practitioners—beef and dairy Regulatory veterinary medicine—state, federal, and/or field services Responsibilities of the committee should include, but are not limited to: Informing and educating the industry regarding Johne’s disease Overseeing financial needs for state Johne’s disease activities Recommending state policies with approval of the appropriate State authority on operating a Johne’s disease program which enhances a Johne’s disease herd status program, reduces the spread of Johne’s disease and assists infected herds in managing or controlling the infection Setting standards for release of information on Program herd status Overseeing appeals of Program herd status Providing input to the USAHA Johne’s Committee National Johne’s Working Group for evaluation and revision of the VJDHS Program The duties of the Johne’s Advisory Committee could be assumed by an existing animal health committee in the State.
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Program Protocol Confidentiality Within the limits of each state’s laws, it is important to maintain as much confidentiality of testing results as possible. At the same time, to promote the program, stimulate the market place to assign added value to animals from program herds and demonstrate the benefits of buying cattle from Johne’s disease status program herds, it is desirable for owners of status level 1–4 herds to disclose their herd status. When possible, program herd owners should have the option of publicly withholding or promoting their herds’ status level. Entry to the Program Herds may enter the VJDHSP by two methods—Standard and Fast Track. All samples for Program testing must be collected by an accredited veterinarian or State or Federal animal health official and submitted to an accredited laboratory. It is recommended that a farm or herd risk evaluation be done before completing herd testing for Level 1 Standard Track or Level 2 Fast Track. This evaluation would inform producers entering the program of existing herd risk factors for the spread of Johne’s disease. A farm risk checklist may also be used as a yearly reminder of existing herd risk factors. Additionally, Program herds should be encouraged to implement Best Management Practices as provided by the National Johne’s Educational package to prevent the introduction and spread of Johne’s disease in their herd. Standard Track The herd must meet identification and commingling requirements described in the definitions. Herds enter the Standard Track Program by Johne’s ELISA testing 30 second lactation or higher animals. No declaration of prior disease freedom is required. Negative test results on this initial test qualifies the herd for Level 1 status. Fast Track The herd must meet identification and commingling requirements described in the definitions. Additionally, the herd owner must submit a signed statement that: I am fully aware of the management and disease history of the herd and the property during the past five years Johne’s disease is not known or suspected to have existed in the herd for the past five years or on the property during the past twelve months
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Cattle are not known to have been introduced from known infected herds during the past five years The above written statement and a negative ELISA test on a statistical subset of second or higher lactation animals qualifies the herd for Level 2 status. States may additionally require the herd veterinarian of record to co-sign the owner statement. Previously Infected Herds Cattle herds previously culture positive for M. paratuberculosis may enter the program by completing Standard Track entry requirements. Infected (positive on an organism detection test) and/or test positive (positive on any Johne’s test) animals must be removed from the herd before Program entry. Johne’s Disease Vaccinated Herds Herds previously vaccinated for Johne’s disease may enter the Program once vaccination has been discontinued. These herds must utilize fecal culture as the only test until enough non-vaccinated natural additions qualify for ELISA testing. The number of animals to test at each level remains the same. Herds Tested Negative Prior to Implementation of this Program Herds Johne’s disease tested negative prior to the implementation of this program may be entered at an assigned Program Level determined after a review by the Johne’s epidemiologist. That review must include: Verification that the herd meets the minimum standards for testing (fecal culture results can be used in place of ELISA results); Future Program tests must be performed in accredited laboratories Risk assessment of the number, source, and testing history of herd additions made after the first qualifying test Additionally, producers wishing to use the Fast Track must make the required written statements for the time period (five years) prior to the first qualifying test. Animals to Test Random sampling will give the most confidence and should be used to select animals for testing when feasible. When possible, the same animals should not be tested in consecutive testing rounds. Animals should be selected to be representative of the herd population. This program uses second or higher lactation animals as the most obvious indication of animal age. Detailed requirements for sample handling and submission must be provided by the testing laboratory.
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Maintaining a Status Level Producers may elect to remain at any level of confidence in either Track by conforming with the program standards and performing an ELISA test on 30 randomly selected animals of second or higher lactation every 10–14 months. A level achievement year for each herd should also be noted as continued monitoring increases confidence the herd is not infected. Testing Intervals Testing intervals are every 10–14 months from the date the test samples are taken. Herds will be removed from the program if the testing interval requirements are not met, unless an extension has been received from the Johne’s Epidemiologist and/or State Cattle Committee. Biosecurity A program herd must have biosecurity measures in place in order to avoid exposure to manure or milk from ruminants of unknown Johne’s disease status. These measures include: Pooled milk from cows of unknown Johne’s disease status should not be used to feed baby calves Manure from Embryo Transfer donors or other “visiting” cows (e.g., transport cows that lay over at program farms for rest or to be milked) should not be allowed to come in contact with the program herd and this manure should not be disposed of on pastures or in a manner which would contaminate pastures or animal feed Exhibition cows and calves (especially under 6 months old) should be hauled in cleaned and disinfected trailers and avoid commingling; (Animal exhibition, consignment sales and transport are considered situations of low M. paratuberculosis infection transmission risk, however prudent care and diligence about biosecurity is recommended) A program herd must not be commingled with or grazed behind susceptible species, (e.g., sheep, goats, farmed deer, camelids, non-program cattle) Program Levels Flow diagrams depicting progression through each status level appears as Appendix II. Percentages on the diagrams represent mathematical estimates of the probability herds at each level or certification are free of Johne’s disease infection based on serial testing. This program does not certify animals free of Johne’s disease. Owners may elect for their herd to remain at any status level by
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ELISA testing 30 second or higher lactation animals every 10–14 months. Maintenance of Level 4 status gives the producer a high level of certainty that their herd is free of infection. With continual maintenance of Level 4 status, it could be assumed that there is negligible risk of infection from Level 4 herds. All samples for Program testing must be collected by an accredited veterinarian or State or Federal animal health official and submitted to an accredited laboratory. If an animal is removed from the herd while ELISA results are pending, a fecal culture should be collected and submitted on hold to the laboratory. This will allow, if the owner wishes, an appeal of herd status to be made if the animal tests ELISA positive (see Appeal Process). Standard Track The standard track is designed to allow entry to the program with a minimal investment of funds and gradually increases the producer’s investment in the program. The standard track will require at least three years and four tests to reach Level 4. Level 1—program entry requirements met, negative ELISA on 30 second or higher lactation animals. A sample size of thirty was selected to optimize herd sensitivity and herd specificity and maintain a fixed cost for all herds entering the program. Level 2—met requirements for Level 1, and negative ELISA on a statistical subset of second or higher lactation animals (see Appendix I for the Herd Subset Testing chart). The Level 2 testing must be completed within 10–14 months of any Level 1 testing. Level 3—met requirements for Level 2 and have negative fecal culture results on a statistical subset of second and higher lactation herd members. Bulls two years of age and older must be included in this testing (see Appendix I for the Herd Subset Testing Chart). The fecal culture must be collected within 10–14 months of any Level 2 testing. Level 4—met requirements for Level 3 and have a negative ELISA on a statistical subset of second or higher lactation animals. Level 4 testing must be completed within 10–14 months of any Level 3 testing. Level 4 status is maintained by achieving negative ELISA results on 30 second or higher lactation animals every 10–14 months. Fast Track The fast track allows producers to proceed to a higher status level of confidence more quickly than the standard track, and requires greater financial investment at program entry. The fast track will allow herds to reach Level 4 in two years with three tests. Level 2—program entry requirements for Fast Track met, negative ELISA statistical subset test of second or higher lactation animals (see Appendix I for the Herd Subset Testing chart).
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Level 3—met requirements for Level 2 Fast Track and have negative fecal culture results on 30 second or higher lactation animals. Level 3 testing must be completed within 10–14 months of any Level 2 testing. Level 4—met requirements for Fast Track Level 3 and have negative ELISA results on a statistical subset test of second or higher lactation animals. Level 4 testing must be completed within 10–14 months of any Level 3 testing. Level 4 status is maintained by achieving negative ELISA results on 30 second or higher lactation animals every 10–14 months. Herd Additions Heifers that have not calved and bulls less than 2 years of age: from herds of equal or higher program levels -or- from program herds which are one level below the purchasing herd. Animals in this category may not be added to Program herds from non-program herds. First and higher lactation cows, bulls greater than or equal to 2 years of age: Level 1–3 herds—from herds of equal or higher level -or- from any other herd as follows: ELISA test of addition(s) in the herd of origin within 30 days prior to entry to the program herd -and- Submission of fecal culture from addition(s) within 30 days of arrival -and- Testing of herd addition(s) in addition to required animal sampling numbers for the next required annual testing. Herd additions are not granted the same status as the receiving herd until this additional testing is negative. Additional risk of infection is incurred when animals are purchased from non-program herds. Non-program herds should be encouraged to ELISA test 30 second or higher lactation animals before a Program herd will purchase from them (i.e., non-program herds should be encouraged to achieve Level 1 status). When possible, additions from non-program herds should be isolated from the program herd and biosecurity maintained until fecal culture results are reported negative.
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Level 4 herds—from herds of equal level -or- from Level 2 or 3 program herds as follows: ELISA test of addition(s) in the herd of origin within 30 days prior to entry to the program herd -and- Submission of fecal culture from addition(s) within 30 days of arrival -and- Testing of herd addition(s) in addition to required animal sampling numbers for the next required annual testing. Herd additions are not granted the same status as the receiving herd until this additional testing is negative. Additional risk of infection is incurred when animals are purchased from herds of lower status. Replacements raised elsewhere: Replacements may only be raised with animals from equivalent status Level herds. Replacements must not be commingled with lesser status level animals or herds. Embryo Transfer/Artificial Insemination (AI): Program herds may utilize semen and embryos from any other cattle herds. However, embryos must be processed according to International Embryo Transfer Society protocols. Embryo transfer recipient cows must meet herd addition requirements. The risk of transmission of M. paratuberculosis from semen is unknown. AI centers are encouraged to routinely test their bulls for Johne’s disease and to remove for sale all semen from bulls found to be infected. All semen used in program herds must be processed according to Certified Semen Services standards. Changes in Herd Status Herd additions: The status of the herd will revert to the status of the lowest animal if Program herd addition requirements are not met. Change of ownership: Herd status is determined by the status of the lowest herd member. Therefore, when ownership of a herd or part of the herd changes and no new animals are added to the herd, the herd level remains the same. When ownership of a herd changes and the herd is commingled with another herd or
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herds, the resulting new herd shall be assigned the lowest level and achievement year of the herds combined to make the new herd. Appeal Process Appealing ELISA positive results: Status of herds with ELISA positive test(s) is “suspended pending confirmation.” Producers may elect to either leave the program or confirm the test results. Confirmation of ELISA-positive cattle will be done by fecal culture. Fecal culture must be submitted within 45 days of notification of ELISA results. If found to be culture-negative, the herd may advance or retain its status Level. Additionally, the animal(s) must be included in the next round of Program testing if still resident in the program herd. Appealing Fecal culture positive results: Fecal culture-positive cattle will be assumed to be infected with M. paratuberculosis and the herd will have its status revoked. Herds may reenter the program at Level 1 by following program standards. If the animal owner wishes to appeal this decision, the herd is assigned a status of “suspended pending appeal.” Appeal may be made using one of three means of proving the animal in question is not infected: Necropsy of the animal with culture and histopathology of at least the ileum, mesenteric lymph node and ileocecal lymph node -or- Biopsy of the ileum (full thickness) and mesenteric or ileocecal lymph node with histopathology and culture of the tissues and culture of a fecal sample taken at the time of biopsy -or- Six separate fecal cultures from the animal on samples collected not less than 30 days and not more than 45 days apart The herd Johne’s disease status will be suspended until all testing is completed. Only negative results on all tests on all samples will allow the herd to advance or retain its Program Level. Appeal of status for other reasons: Herd owners may appeal any decision or discuss extenuating circumstances that prevent compliance with the program rules to the State Johne’s Advisory Committee: A sample size of 30 was selected to reduce cost while maintaining acceptable accuracy
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A history of Johne’s disease freedom for five years prior to program entry adds sufficient confidence to allow Fast Track herds to test 30 animals rather than the statistical subset used in the Standard Track to obtain Level 3 status APPENDIX I Herd Subset Sampling PLEASE NOTE: The sample numbers below have been calculated based on the following assumptions: The cattle to be tested are in second or higher lactation For these calculations, 25 percent test sensitivity of the ELISA and 40 percent test sensitivity of the fecal culture were assumed (this were the consensus estimates of the Herd Status Committee for subclinically infected cows in first of higher lactation, and no changes were made for the older population sampled For these calculations, 100 percent test specificity of the ELISA and fecal culture was assumed (given follow-up of all ELISA positives with fecal culture) The confidence of detecting infection (at least 1 test-positive cow), if present at a true prevalence of 2 percent, is 95 percent Sampling without replacement (hypergeometric distribution) Table B-1. Testing Sample Size Number of cows in herd of 2nd or higher lactation Number of cattle to sample (2nd lactation or higher) Less than 300 Test all Test all 400 Test all 313 500 Test all 324 600 531 332 700 540 338 800 547 342 900 552 345 1000 580 360 Note: In smaller herds, all cattle second or higher lactation must be tested. In herds with fewer than 30 second and higher lactation animals, first lactation animals must also be tested.
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APPENDIX II Voluntary Johne’s Disease Herd Status Program Standard Track
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Voluntary Johne’s Disease Herd Status Program Fast Track
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Voluntary Johne’s Disease Herd Status Program Key to chart—Definition of tests The interval between tests is 10 to 14 months, except for confirmatory testing.
Representative terms from entire chapter: