PROCEEDINGS

NINETY-NINTH ANNUAL MEETING

of the

UNITED STATES ANIMAL HEALTH ASSOCIATION

JOHN ASCUAGA'S NUGGET HOTEL

RENO, NEVADA

October 28 - November 3, 1995

Table of Contents


REPORT OF THE COMMITTEE ON JOHNE'S DISEASE

Chairman: Dr. Robert H. Whitlock, Kennett Square, PA

Vice Chairman: Dr. Michael T. Collins, Madison, Wisconsin

J. Adams, MD; B. Addison, MO; R.D. Angus, ID; M. Anthony, CDN; T. Booher, OR; D. Bruno, NY; B. Byrum, OH; H.M. Chaddock, MI; E. Chandler, CO; Y. Chang, NY; M.T. Collins, WI; J. Conner, IN; R. Cook, NY; J. Corbett, CA; J.P. Davis, MD; R.W. Dellers, WI; D. Donch, MI; R.J. Eisner, NJ; M. Essey, MD; K. Eugster, TX; W.H. Fales, MO; R. Frost, CA; T. Fuhrmann, AZ; R. Galuer, OH; W. Goodwin, FL; K. Gordon, ME; V. Hulse, OH; D. Johnson, SD; J. Kaneene, MI; A. Kennel, MN; D. Lein, NY; J. Lemmermen, FL; G. Magnes, SD; A. Mateos, MX; L. McPhail, OH; R. Meyer, CO; R. Nelson, VT; J. O'Donnell, ME; B. O'Niel, NZ; J. Olson, FL; K. Olson, MD; R. Olson, MD; R. Oltgen, MD; J. Oosterhuis, CA; J.B. Payeur, IA; V. Patton, NY; C. Peterson, NY; J. Rais, CO; P. Rogers, CO; R. Rogers, Cdn; C.A. Rossiter, NY; H.L. Rubin, FL; S. Seubert, WI; S. Singh, KY; K. Smith, ME; D. Sockett, WI; J. Stabel, IA; S. Stehman, NY; R. Streuger, MO; D. Thorpe, SD; C.O. Thoen, IA; M. Van Buskirk, PA; W. Wagner, DC; S. Wells, CO; M. Westendorf, NJ; G. Wilder, MO; D. Whipple, IA; R. Whitlock, PA; H. Whitford, TX; C. Wolfe, MN; E. Zirkle, NJ.

The committee meeting began at 1:30 p.m. on October 31, 1995 and included 19 reports and presentations and vigorous discussions and concluded at 6:15 p.m. Attendance included 24 of the 42 committee members and 44 guests for a registered total of 68 (some attendees did not sign the register).

The purpose of the Johne's Disease Committee as written in Article II of the USAHA was read aloud to remind committee members of the tasks set forth for the committee.

"The purpose of the Committee on Johne's Disease is to facilitate control and eventual eradication of paratuberculosis by providing information and guidance on diagnosis and control of infection to appropriate federal, state, and industry personnel.

The committee also provides the latest information to animal diagnostic and regulatory agencies concerning diagnostic methods for Johne's disease, assists in helping identify the most sensitive and specific tests available for paratuberculosis diagnosis, and fosters the establishment of standardized diagnostic tests including culture and serologic tests for the detection of M. paratuberculosis.

The committee identifies the prevalence and economic losses associated with paratuberculosis infection in ruminants and promulgates distribution of information on how to best to control and manage the disease."

Formation of National Johne's Working Group (NJWG):

The committee chair described actions taken on the recommendations and resolutions from the last Johne's committee meeting. A letter was sent on November 18, 1994 to each Johne's committee member requesting input concerning the establishment of a task force on the relationship of M. Paratuberculosis to Crohn's disease. This letter outlined a draft of the charge to the task force and listed potential constituent groups as participants on the task force. Several responders provided additional insight about the formation of the task force. With many important ramifications for both the USAHA and producer groups, the chair of the Johne's Committee and the president of the USAHA, Dr. Wes Towers, agreed it would be prudent to have the task force, later to be called the National Johne's Working Group (NJWG) appointed by the President of the USAHA. During a meeting of the USAHA executive committee in Washington, DC at the National Cattleman's Association office on February 28, 1994, Dr. Wes Towers, President USAHA, appointed John Adams (National Milk Producer's Federation), Gary Weber (National Cattleman's Association) and Robert Whitlock (Chair Johne's Committee) as co-chairs of the National Johne's Working Group (NJWG). They in conjunction with Dr. Towers and the USAHA executive committee, identified the following individuals (organizations) to serve on the NJWG:

Members of the NJWG with organizational affiliation:

Member Organizational Affiliation
Adams, John B. Director - Milk Safety and Animal Health for National Milk Producers Federation
Arnoldi, Joan Director, National Veterinary Services Laboratory, Ames, Iowa
Byrne, Robert D. Jr. Assistant Director, Product Safety & Technology, International Dairy Foods Association, Washington, DC
Bulaga, Leslie Epidemiology Officer, USDA APHIS Veterinary Services, Trenton, NJ
Bursey, R.G. Sr. Vice President, Dairy Management, Inc., Arlington, VA
Collins, Michael University of Wisconsin, Madison, WI
Essay, Mitch USDA - Cattle Diseases, Riverdale, MD
Hansen, Donald American Association of Bovine Practitioners, Oregon State University, Corvallis, OR
Luchsinger, Donald USDA, APHIS, VS, Washington, DC
Nelson, Richard Exec. Assistant - Domestic Affairs, Holstein Association, Brattleboro, VT
Olson, Kenneth, E. American Farm Bureau Federation, Director, Dairy Department, Park Ridge, IL
Rossiter, Christine Cornell University, Ithaca, NY
Sayler, Allan, R. Senior Milk Specialist, Food and Drug Administration, Washington, DC 20204
Slack, Glenn N. Executive Director, Livestock Conservation Institute, Bowling Green, KY
Stabel, Judith USDA/ARS/NADC, Ames, Iowa
Thorpe, Daryl K. Representing the AVMA Council on Public Health and Regulatory Medicine, Pierre, South Dakota
Thoen, Charles representing the AAVLD Mycobacterial committee, Ames, Iowa
Towers, H. Wesley representing the USAHA, Dover, DE
Van Kruiningen, Herbert J. College of Agriculture & Natural Resources, University of Connecticut, Storrs, Ct.
Vogel, Lyle AVMA, Schaumburg, Illinois
Weber, Gary M. Assoc. Director Animal Health, National Cattlemen's Association, Washington, DC
Walton, Tom Director, NADC/USDA/ARS, Ames, Iowa
Wells, Scott USDA/APHIS/VS for the NAHMS's Program, Fort Collins, Colorado
Westendorf, Michael Rutgers University, New Brunswick, NJ
Whitlock, Robert H. University of Pennsylvania, Kenneth Square, PA
Zimmermann, Bob American Society of Animal Science, Bethseda, MD.

John Adams, Co-chair, NJWG, presented an update on the activities of the NJWG. He stated that the first meeting of the NJWG was held April 4, 1995 in Kansas City, MO, at the LCI meeting with 14 members and 15 guests present. The following four subcommittees were formed: Economics--Chair Ken Olson, Johne's Control Programs--Chair Mitch Essey, Research--Co-chairs Judith Stabel and Tom Walton, Diagnostics--Chair Joan Arnoldi. Several objectives were outlined for each of the sub-committees. The second meeting of the NJWG was held during the AVMA meeting in Pittsburgh on July 12, 1995, at the Hilton Towers Hotel. Each subcommittee presented a report with brisk, energetic discussion on several issues including the CFR, the upcoming NAHMS' Diary '96 program, milk pasteurization studies and the agreement of USDA/APHIS/NVSL to conduct Johne's check tests for diagnostic laboratories that may be participating in the Johne's certification program.

Mr. Adams reviewed a draft of the mission statement and objectives for the NJWG.


Ongoing Johne's Research At The National Animal Disease Center

J. R. Stabel

USDA/ARS/NADC/Leptospirosis/Mycobacteriosis/Brucellosis Research Unit, Ames, IA USA

Paratuberculosis (Johne's Disease) is a chronic, progressively enteric disease of ruminants caused by infection with Mycobacterium paratuberculosis. Clinical disease is characterized by chronic or intermittent diarrhea, emaciation, and death. Further economic losses in affected cattle are caused by reduced milk production and poor reproductive performance. Although the economic impact of paratuberculosis on the national cattle industry has not been determined, it is estimated to exceed $1.5 billion/year.

Diagnosis of subclinical paratuberculosis is difficult. Diagnostic tests based upon evaluation of humoral or cell- mediated immune responses to M. paratuberculosis antigens, bacteriologic culture of feces or tissue specimens, and most recently a nucleic acid probe and a polymerase chain reaction (PCR) assay for identification of M. paratuberculosis in fecal and tissue samples have been developed. Immunological diagnostic tests suffer disadvantages from false positive and false negative results caused by the lack of specificity of antigens used to elicit or detect responses. Bacteriologic culture is the most definitive method of diagnosis but is time consuming and labor intensive. A nucleic acid probe developed from an insertion sequence of M. Paratuberculosis has been used in conjunction with amplification of the target sequence using polymerase chain reaction to detect M. Paratuberculosis in fecal samples. Unfortunately, in our laboratory the probe test is only 60% as sensitive as fecal culture. Therefore, the need of more sensitive diagnostic tests to detect subclinical shedders is immediate.

Recent evidence has linked Crohn's disease in humans to infection with M. paratuberculosis. Although not characterized as a zoonotic agent, M. paratuberculosis has been identified in intestinal biopsy tissue from patients with Crohn's disease, an inflammatory enteritis in humans. One possible source of human exposure to M. paratuberculosis is the consumption of milk or dairy products since presence of paratuberculosis DNA has been documented in cow's milk obtained from retail markets in Great Britain. It is not certain at present whether current pasteurization and processing procedures in the United States are adequate to destroy high numbers of paratuberculosis in the milk, creating a possible health hazard for consumers.

Current objectives for research at the NADC are: 1) to develop new and modify existing diagnostic procedures for the detection of subclinical paratuberculosis; 2) determine a possible etiological role of M. paratuberculosis in Crohn's disease in humans and potential exposure to this pathogen through contaminated dairy products; 3) isolate and characterize M. paratuberculosis-specific proteins which can be used as diagnostic tools; and 4) investigate genetic association between resistance/susceptibility to M. paratuberculosis and disease state of the animal.

Cultivation of M. paratuberculosis from fecal specimens is considered to be the definitive diagnostic test for bovine paratuberculosis. We have recently modified the fecal culture method to include a centrifugation step which aids in concentration of bacteria. This method improves detection of M. paratuberculosis in fecal samples 10-fold without contamination problems associated with previously used techniques. We have also evaluated the use of -interferon production of paratuberculosis. When stimulated with preparations of M. paratuberculosis in vitro, peripheral blood mononuclear cells isolated from animals with subclinical paratuberculosis produced significantly greater amounts of -interferon compared to noninfected control animals.

A possible role of M. paratuberculosis in the etiology of Crohn's disease in humans has led to studies evaluating milk pasteurization conditions and potential survivability of this pathogen in dairy products. It is unknown whether current standard conditions of milk pasteurization are adequate to kill contaminating M. paratuberculosis. Experiments are being conducted to determine optimal times and/or temperatures for maximal killing of M. paratuberculosis in milk. A small-scale pasteurization unit purchased from a commercial vendor is being utilized to conduct these experiments. These experiments are evaluating various field and laboratory strains of M. paratuberculosis, including isolates from Crohn's patients.

Due to the high degree of similarity in their genetic makeup, cross-reactivity between M. paratuberculosis and M. avium in diagnostic tests is a major problem. Identification of M. paratuberculosis-specific antigens would circumvent this problem, however, there is currently very little information available in this area. At the NADC, two M. paratuberculosis-specific proteins were recently identified which do not cross-react with M. avium. Genetic cloning and expression systems were developed for M. paratuberculosis and affinity-purified antisera for screening clones was prepared. With this methodology, an M. paratuberculosis-specific gene was isolated and found to be immunogenic.

There is a significant association between the major histocompatibility complex in cattle (BoLA) and host immunity. The BoLA class I and class II genes encode for cell-surface proteins which are important in the regulation of immune responses. There is currently no information available describing the relationship between paratuberculosis in cattle and expression of BoLA class II genes. We have initiated studies to screen herds for paratuberculosis and correlate expression of specific alleles within the gene locus with infection status of cows as determined by fecal shedding of M. paratuberculosis.


JOHNE'S DISEASE

THE INTERNATIONAL PERSPECTIVE

Michael T. Collins, DVM, PhD and Elizabeth J.B. Manning, MPH, DVM

Department of Pathobiological Sciences

University of Wisconsin School of Veterinary Medicine

Madison, Wisconsin

Why is it of interest to assess the global prevalence of Johne's disease? With agriculture, as with any aspect of modern life, neighbors' conditions affect one another. As the definition of "neighbor" is no longer limited to geographic proximity but includes those with whom we work and trade, unaffected by distance, it behooves us to appreciate circumstances beyond our borders.

In all likelihood, Johne's disease is to be found in every country. Being free of the disease is probably more a function of how hard one has looked than a true lack of incidence. Knowing that paratuberculosis is at least a potential if not actual concern for every country should promote a realistic, useful international perspective of the disease. A complete grasp of the extent of paratuberculosis will assist all those affected in the many ways possible by the disease, whether through regulatory activities, livestock management of medicine, research, and public health. This assistance will take the form of developing practical management, regulatory and economic policies. These policies, having been based on actual conditions, vs. abstract extrapolations, will support a uniform global arena for agricultural endeavors.

Specific realms to consider when assessing the international impact of Johne's disease include:

1. Trade barriers

As illustrated by the situation in Australia (see below), having M. paratuberculosis test positive herds can affect all aspects of trade. Prices can slide, demand drop, export regulations be required, etc. Additionally, dissimilar barriers between different countries can make trade more cumbersome and costly. In all probability, barriers will soon also address products made from animals with Johne's disease. These products currently are free of restrictions in all international markets.

2. Slowed global genetic improvement

Dissemination of genetically superior livestock can be hindered by the perception that the buyer is free of disease and the seller has some degree of prevalence. Actual genetic improvement will be prevented through the purchase, often with scarce resources, of untested and infected animals that then infect the recipient herd. Zoological parks exist on every continent. Johne's disease is a threat to the continued health and propagation of these rare collections.

3. Policies based on inconsistent testing methodologies

Conclusions based on interpretations of different tests applied in varying manners can be more expensive and unproductive than having made no conclusions at all. Testing methodology, results interpretation and the successes and failures in management application of test results should be shared among countries.

4. Costs (1,2)

The direct and indirect costs of Johne's disease stem from many realms. Losses with which we are most familiar include reduced milk production and weight loss due to poor feed conversion and clinical/subclinical disease, increased culling rate, time and labor both complying with and managing regulatory programs, testing expenses and research. An additional loss for developing nations is an impairment of economic development programs, as investments in livestock are wasted. Development of ecotourism programs (such as photo-safaris) can also be hampered by the threat of cross-infection between wildlife in national parks and surrounding domestic livestock. Impediments to tourism can curtail a major component of the GNP and the country's only source of foreign exchange.

5. Zoonosis

The continued investigation of the possible association between Crohn's disease and M. paratuberculosis could benefit from a thorough global analysis of the incidence of both diseases.

6. Research and control

An assessment of the international prevalence of Johne's disease can help prioritize research efforts and funding, support the establishment of effective global disease control programs and better determine the cost-effectiveness of efforts intended to control and/or prevent the spread of paratuberculosis worldwide.

Methodology

To gain an impression of the prevalence of Johne's disease internationally, a short survey was developed and faxed to a subset of the IAP membership. A literature review was conducted as well, and government publications were canvassed for any information pertaining to the disease.

It goes without saying that the topic of this paper, "the international perspective", is in fact a compilation of general impressions given the testing and interpretation difficulties inherent with Johne's disease. The most common impression received was the lack of information on any basis, be it local, national or international. As a Canadian respondent put it, "There is an amazing paucity of information n the prevalence of Johne's disease."

Given this "paucity", we will give a brief description of the world's exposure to Johne's disease. In most cases, the data is bimodal - either a country has it or it doesn't.

JOHNE'S DISEASE POSITIVE LOCALES

Africa

In countries of the African continent, testing for M. paratuberculosis runs the gamut from never being done to gene probe confirmation of BACTEC cultures. We were able to find information about 12% or 6 of the continent's 49 countries: Kenya, Nigeria, Sudan, Tunisia, Zambia and South Africa. (Only the Sudan and Kenya are contiguous, and that minimally: Kenya shares only 1/20th of Sudan's border.) In this case, "finding information" meant discovering that at least one case had been reported in recent years. In South Africa the disease has been reported in both sheep and cattle with a focus of isolated herds in the wetter regions of the country (Natal, E. Transvaal). The disease is believed to be neither highly prevalent nor of major significance in this country. In Zambia paratuberculosis is reported to be a greater problem in sheep than in cattle and Tunisia's reports dealt only with camels. No information has been found to date on the other 43 African countries, and therefore no conclusions can be drawn about Johne's disease prevalence in those areas.

Australia

New Zealand reports that paratuberculosis is widespread in dairy cattle and goats plus is of concern in sheep and beef cattle as well. The number of recorded infected dairy properties has jumped dramatically over the last 4 years, and it is believed that this registry of infected premises understates actual prevalence. In concert with an increase in the extent of the disease (also evidenced by a doubling in vaccine sales in a year), all research was stopped.

Lesson from Australia - Potential trade barriers

Each of the 7 Australian states manages and monitors its own agricultural activities. Of the 7, Johne's disease is endemic in one state, positive herds are found in two others (at a reported prevalence of 17% and 1.4%) and the remaining 4 states report themselves free of the disease. Sheep and cattle trade among the states is stymied, with demand, marketing and prices affected by the perception, as well as the certainty, of Johne's disease prevalence.

Asia

China, Japan, India, Korea, Kazakhstan, Nepal and the Philippines are countries in Asia with contemporary, albeit infrequent, reports of Johne's disease. Japan's information was the most extensive for the region, reporting an annual average of 212 cases of clinical bovine paratuberculosis over the last five years. These cases were confirmed at slaughter. As the United States government continues its efforts through USAID to develop dairy industries in Pacific Rim countries, the need for Johne's disease testing for the new industries should provide a sense of the prevalence in this region.

Europe

Incidence of Johne's disease is reported to be increasing in the Netherlands, Finland, Italy and Scotland. In other parts of the European continent, no change in incidence has been noted over recent years. Countries belonging to the constant incidence category are Norway, Denmark, Portugal and Belgium, France, Cyprus, the Czech Republic, Greece, Hungary, Iceland, Slovakia, Spain, Switzerland and Turkey report that cases of paratuberculosis have been found within their borders but offer no guess about the direction in which incidence is moving.

Lesson from Sweden - If you look, you will find it

From 1989 to 1994, only seven cases of Johne's disease were identified. Found in six herds, they all were traced to imports from Denmark. A July 1994 publication stated that "Swedish livestock are free of paratuberculosis". In March 1995 however, a Swedish herd was found to be positive and was slaughtered. Seventy contact herds are now under investigation. Sweden's continued testing of its livestock after its having been deemed paratuberculosis-free was valuable.

Central and South America

We found information about only three countries in this region - Mexico and Brazil which report test positive cases and Argentina which believes incidence is increasing.

Summary

We close with another quotation from a survey respondent. "The incidence of Johne's disease appears to be increasing due to the veterinarian's interest and attention." With greater scrutiny comes increased appreciation of the extent of problem. We believe no region in the world is free of M. paratuberculosis infection in its ruminant livestock and that every region's agricultural sector therefore is hampered to some extent by Johne's disease. We also believe that the resources to address paratuberculosis-related problems on a state-wide and national basis will continue to shrink as financial constraints are felt in government and other sectors. More extensive pooling of resources and efforts on an international basis may be one of the few remaining ways of continuing efforts to improve diagnosis and management of this disease.

References

1. I.J. Gill. The economic impact of Johne's disease in cattle in Australia. Johne's Disease (proceedings) Milner, A. R and Wood, P.R. p. 36-40. 2. Jones, R.L. Review of the economic impact of Johne's disease in the United States. Johne's Disease (proceedings) Milner, A. R and Wood, P.R. p. 46-50. 3. R.J. Chiodini. The history of paratuberculosis (Johne's Disease) - A Review of the Literature 1985- 1992. International Association for Paratuberculosis, Inc. 1993. 4. S.S. Bastianello and H.F. Huchzermeyer. Pathological, bacteriological and serological findings in 100 ewes and their fetuses from a paratuberculosis sheep flock in South Africa. Proceedings of the Fourth International Colloquium on paratuberculosis. Chiodini, Collins, Bassey. 5. Future Management of Johne's Disease in New Zealand. Ministry of Agriculture Regulatory Authority, Wellington. July 19, 1995.


NJWG subcommittee of the report summary:


Ken Olson, Chair

Subcommittee on the Economic Impacts of Paratuberculosis

Members of economics subcommittee: Michael Collins, Kenneth E. Olson, Steven Ott, Christine Rossiter, Michael Westendorf

Economics subcommittee objectives:

1. Review the literature and summarize studies evaluating the economic impact on the of Johne's Disease for producers.

2. Compile other information relative to economic impacts on the industry.

3. Compile listing of reported incidence of Johnes:

4. Provide input on the NAHMS' dairy survey relative to Johne's disease.

Dr Collins reported that his review of the literature and a recent international fax survey he conducted indicated that no country is free of Johne's disease.


Dr. Mitch Essey, Chair

Subcommittee to review State Control Programs for Johne's Disease

Members of subcommittee: Chris Rossiter, Don Sockett, Leslie Bulaga, Lee McPhail, Mike Westendorf, Debbie Donch, and Elizabeth Chandler Porter.

Objectives:

  1. To review all state Johne's control and certification programs
  2. To recommend a unified approach to controlling Johne's disease
  3. To minimize regulatory barriers to Johne's disease control
  4. To amend the regulations to fulfill the need for a workable, acceptable effective Johne's control initiative.
  5. To develop a strategic plan for an industry-led voluntary National Johne's control program, supported by industry and acceptable to state and federal animal health regulatory entities.

Regulatory issues about paratuberculosis included in CFR Part 80 and Part 72 were reviewed. The final rule to retain Johne's Disease (paratuberculosis) in the CFR and to specifically change the location of the brand from the jaw to the left hip was passed September 19, 1995. At this time, as has been the case for many years, there is no "official Johne's test" approved by the Secretary of Agriculture. Thus part 80 of the CFR has not been involved but remains on the books.


Dr. Judith Stabel, Co-Chair

Subcommittee on "Research Status and Priorities"

Members of subcommittee: Thomas Walton Co-Chair, Ray Sweeney, Michael Collins, John Kreeger

Objectives:

  1. Determine and prioritize research objectives for Johne's disease
  2. Update on current (state-of-the-art) techniques for the diagnosis of Johne's disease
  3. Report on most current research publications.

Responses to a letter sent to 15 investigators requesting their input about priorities for Johne's disease research were tabulated by Dr. Stabel and are listed:

Main Priorities:

Lesser Priorities:

Data from three pasteurization studies being conducted at this time are not complete.

Preliminary results from the milk pasteurization studies suggest:

  1. The number of organisms added (often 10 per ml) to the milk are artificially high and may not be in the same form as occurs naturally (intracellular and in clumps).
  2. Pasteurization at 72= C for 30 minutes may kill most M. paratuberculosis but short pasteurization times at higher temperature may not kill most of the organisms.
  3. Some strains of M. paratuberculosis may vary in their sensitivity to pasteurization time and temperatures. The strains isolated from patients with Crohn's disease were more heat susceptible than bovine strains.
  4. The preliminary results of the three studies suggest that some M. paratuberculosis organisms may survive normal pasteurization processes. However no data exists to suggest that viable M. paratuberculosis have been isolated from pasteurized milk in the marketplace. Reports from England indicate M. paratuberculosis DNA to be present in marketed milk, but viable organisms were not found in that milk.


Dr. Joan Arnoldi NVSL, Chair

Subcommittee on "Diagnostic Issues"

Members of subcommittee: Janet Payeur, Howard Whitford and Pat McDonough.

USDA/NVSL will be conducting Johne's check tests for both fecal culture and antibody detection systems in the near future. The samples (30 sera and 20 fecals) will be submitted to participating laboratories in November 1995. Approximately 14 laboratories will participate in the first check test. A poll of laboratories conducting tests for Johne's indicated the following:

Diagnostic Test Number of laboratories performing the test
AGID 26
CF 22
IDEXXELISA 16
Gamma Interferon 1
Fecal Culture 35
DNA Probe 7
DNA Probe (in house) 2


Pasteurization of milk report - M. Collins.

A report on scientific studies done at the University of Wisconsin, funded by the Wisconsin Milk Marketing Board, to evaluate the ability of M. paratuberculosis to withstand pasteurization was presented by M.T. Collins. Both human and animal strains of M. paratuberculosis, suspended in lactate buffer or raw milk, were tested at five different temperatures and a minimum of five different heat exposure times. The results were shown graphically as thermal death curves. Comparison of these thermal death curves to present pasteurization methods suggests that M. paratuberculosis, if found in raw milk, would be killed by the low temperature, long time (vat method) of pasteurization but not by the high temperature, short time (HTST) method. Dr. Judy Stabel, NADC, indicated that these findings are in agreement with similar studies done at her laboratory.

Dr. Stabel, NADC, described research to evaluate the gamma interferon test to detect clinical and preclinical M. paratuberculosis infected cattle. The data are encouraging and suggest that this test will be useful to detect infected animals earlier than by other diagnostic methods.

Mr. Ken Smith, IDEXX Laboratories, Inc., described several modifications to the M. paratuberculosis Antibody test Kit sold by his company. In December a kit will be available in "strip well format" to permit laboratories with a smaller volume of Johne's testing to use the test more easily. Also, it will be packaged in units with fewer tests per package to make the kit more affordable for small volume laboratories. Modifications in antibody conjugate to permit use of the assay on multiple species of animals and development of software to make data management and reporting of results easier are potential improvements under study.


NAHMS Dairy '96 project was outlined by Dr. Scott Wells.

The basis for the NAHMS' program is found in the Animal Industry Act of 1884 which directed the predecessor of Animal Health Inspection Services' (APHIS), the Bureau of Animal Industry, to "collect such information...as shall be valuable to the agricultural and commercial interests of the country". Presently NAHMS's activities are led by the Fort Collins, Colorado staff, with fifteen members to carry out their mission with broad cooperation from producers, veterinarians, Universities, State Departments of Agriculture and others. The Objectives for the Dairy '96 Study are:

  1. Estimate the national and regional prevalence of specific pathogens in dairy cattle, including M. paratuberculosis (Johne's disease), bovine leukosis virus, and Neospora sp. A further objective is to provide information on factors associated with M. paratuberculosis in cattle to support the development of herd certification programs. The resulting information is intended to support preventative efforts directed toward these key bovine pathogens. Disease pathogens were identified as a priority by focus groups representing dairy producer groups, veterinary/dairy scientist groups, and USDA:APHIS.
  2. Describe baseline dairy cattle health and management practices used on U.S. dairy operations.
  3. Describe management practices used to assure the production of quality dairy products on U.S. dairy operations.
  4. Describe the incidence of digital dermatitis (hairy heel warts) on U.S. dairy operations.
  5. Evaluate factors related to Salmonella in dairy cattle. 6. Provide a profile of animal waste handling systems used on U.S. dairy operations.

Twenty states, which contain approximately 83% of the U.S. dairy cattle will be given the opportunity to participate in the study. Approximately 4500 initial contacts will be made in these 20 states. The estimated response rate to the first phase of the study is 50%. An estimated 700 producers will voluntarily participate in the second phase of the study which includes a current assessment of Johne's disease. An estimated 30 adult cattle will be randomly chosen from each herd for blood samples to be tested using the IDEXX absorbed Johne's ELISA test. NVSL has agreed to do the serologic testing on the 18,000 to 20,000 sera to be collected. The sampling scheme should detect at least one infected cow in a herd with a true prevalence of 10%, with 95% confidence, if the test used is 100% sensitive and specific. This will help define the herd prevalence of Johne's disease in the nation's dairy herd.

This study should determine:

  1. The proportion of dairy herds infected with M. paratuberculosis.
  2. Producer awareness of Johne's disease.
  3. An assessment of the relationship between management factors and the seroprevalence of Johne's disease.
  4. An initial assessment of the economic losses attributable to Johne's disease.

The time line for the Dairy '96 is:

January 1996: Phase I-NASS conducts first interview with producers to collect baseline management information and obtain permission to give their names to APHIS-VS/State-VMO for second phase of the study.

February to May 1996: Phase II - APHIS-VS/State-VMO administers second health questionnaires and conducts biological sampling.

Report of subcommittee on changes to CFR part 80, Dr. Max Van Buskirk.

The primary changes needed to update the CFR part 80 that pertains to Johne's disease are referable to the designation of an official test (currently the US Secretary of Agriculture has no designated official test), substituting "Johne's disease" for "paratuberculosis" and elimination of the necessity for branding. Discussions with state veterinarians indicated little support for the designation of an official test, such as the fecal culture, at this time.

Update on State Programs.

Brief reports were made by representatives from New York, Michigan, Ohio, Pennsylvania, Wisconsin, Texas, New Jersey, Maryland, Kentucky, Minnesota, and South Dakota. Each state program is somewhat unique and all are frustrated by a lack of resources to meet the needs of herd owners wanting to try and ride their herds of Johne's disease. The cost of testing is subsidized totally in some states, partially in others and not at all in a few. District veterinarians in most states try and visit owners of infected herds to help educate them about Johne's control practices. The impression by all states is that Johne's disease is increasing in incidence. The rate of testing for Johne's is also increasing.

M.T. Collins announced that the next international meeting dedicated to research on Johne's disease, called the Fifth International Colloquium on Paratuberculosis, will be held in Madison, Wisconsin, September 29-October 4, 1996. The meeting occurs at the same time as the World Dairy Expo in Madison providing an interesting opportunity for persons interested in dairy and cattle and the dairy industry.

Mission statement and objectives for the NJWG:

Drafts of both were reviewed by the committee.

A motion to support the draft mission statement for the NJWG was made and not passed. A second motion to table further action on the mission statement until next year's meeting was passed. Several suggestions were made to improve the mission statement. The draft mission statement was as follows:

The National Johne's Working Group (NJWG) will serve as a resource for animal agriculture in assessing any potential association between Johne's and human health. Recognizing that Johne's disease has major economic implications for producers, the NJWG will develop and coordinate implementation of a national Johne's program. This program will be designed to protect the public and animal health, reduce the economic burden upon producers and bring about a uniform approach for control, herd certification, and eventual eradication of this insidious and costly disease in the United States.

A motion was made and passed to endorse the objectives for the NJWG. The objectives were as follows:

  1. NJWG will evaluate information suggesting M. paratuberculosis is a zoonotic pathogen and assess the likelihood that animals serve as a reservoir of infection.
  2. NJWG will evaluate the potential for the organism to contaminate foods of animal origin.
  3. NJWG will identify and encourage research needed develop a strategy for a control and herd certification program.
  4. NJWG will evaluate the domestic and international economic impacts of Johne's disease and develop recommendations for updating currently suggested good management practices which can be employed by producers to prevent entry and spread of the infection in livestock populations.
  5. NJWG will develop a set of policy objectives and goals to enhance development and implementation of the strategy for a Johne's disease control and herd certification program.

Function of the working group with the Johne's Committee:

Discussion centered around the expanded role of the NJWG and the Johne's Committee. Many members believed the NJWG with their broadly based objectives has assumed many objectives of the Johne's Committee as described in the purpose statement for the committee. To facilitate the goals of both the committee and the NJWG, committee members and others, both the NJWG and the NJWG subcommittees will be expanded to include additional committee members and other interested persons.

The meeting was adjourned at 6:15 p.m.