Conquering Johne's disease with a U.S. certification program
Johne's disease (paratuberculosis) is a growing concern to U.S. cattle producers and a model herd certification program is being developed to form more consensus on a national level about Johne's disease and create greater uniformity in herd certification programs between the states.
Currently, approximately 12 states have a herd certification program for Johne's disease. National organizations have stepped up by forming a National Johne's Working Group (NJWG) to help develop and implement a National Johne's Program. The NJWG was created by the U.S. Animal Health Association (USAHA) Johne's committee. Currently, the working group has developed plans for a certification-like program and educational materials, and will present them at the U.S. Animal Health Association meeting in October.
Johne's (pronounced "Yo-nees") disease is a chronic wasting disease marked by diarrhea that does not respond to treatment. Cattle, bison, cervids, sheep and goats can become infected with Johne's disease through feed or water contaminated with infected feces, or from bacteria on the teat or udder of the mother.
An earlier model Johne's disease herd certification program developed in 1993 was not favorable because of the amount of testing required and the associated costs. In 1997, the USAHA NJWG appointed a committee to try to design a more affordable and scientifically sound herd certification program.
The recommended Voluntary Johne's Disease Herd Status Program (VJDHSP) is intended to provide flexibility for herd owners and reduce the cost of testing from that of the previous program. This program is designed to serve as a minimal requirement for operation of a scientifically sound program to identify herds of low risk of M. paratuberculosis infection.
According to Leslie Bulaga, co-chair of the NJWG certification subcommittee, an important consideration was that the working group didn't want 48 different certification programs across the U.S. "We want a Level 2 cow in Florida to mean the same as a Level 2 cow in Oregon," says Bulaga. "We need uniformity among the states."
The certification subcommittee hopes that these guidelines will become the basis for national uniformity and create equity among different state Johne's disease programs. The certification subcommittee has developed minimal guidelines for the states, but each state can make their guidelines more stringent, states Bulaga.
The resulting herd status program has been developed in two phases. According to Bulaga, the first phase consisted of developing a testing scheme. This consisted of deciding what animals to test and how they should be tested. This testing portion of the program was submitted for discussion at the NJWG meeting held in conjunction with the Livestock Conservation Institute's annual meeting in March 1998.
The second phase consisted of designing all the other things needed in a herd status program, states Bulaga. Discussion here was raised on what labs could be used and how to select animals to be added to certified herds.
The recommended VJDHSP is divided into four status levels that herds can achieve. The status levels are 1, 2, 3 or 4 with each level increase indicating higher confidence in the Johne's disease free status of the herd.
The model program allows herds to enter the VJDHSP by two methods— Standard and Fast Track. According to the model program, samples for Program testing must be collected by an accredited veterinarian or State or Federal animal health official and submitted to an accredited laboratory. Additionally, the program encourages producers to implement Best Management Practices to prevent the introduction and spread of the Johne's disease in their herd.
For a herd to enter the program on the standard track, the herd must meet identification requirements by 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. Herds can enter the Standard Track Program by Johne's ELISA testing 30 second lactation or higher animals. A sample size of 30 was selected to reduce cost while maintaining acceptable accuracy.
The Fast Track method for producers to enter the VJDHSP consists of the producer signing a statement that he/she is 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; and cattle are not known to have been introduced from known infected herds during the past five years. Additionally, the producer must provide a negative ELISA test on a statistical subset of second or higher lactation animals. This negative test would qualify the herd for Level 2 status.
At the recent National Cattlemen's Beef Association meeting in July 1998, model rules and recommendations were drafted, reviewed and submitted to the NJWG for approval. A version of the VJDHSP was sent to all state veterinarians, cattle breed associations, USDA, APHIS Veterinarians and veterinarians in charge, veterinary groups such as American Association of Bovine Practitioners and American Veterinary Medical Association and other interested parties. These groups had approximately three weeks to comment on the draft proposal. According to Bulaga, the comments received will be incorporated into the final presentation at USAHA.
"Most of the comments received so far have been generally favorable, but a few reviewers want some changes," Bulaga says.
One of the areas of the program which was modified in the latest draft is the issue of herd additions. "The proposal has to design a way that program herds can bring in animals in a practical and safe way," she says. "We are trying to make it flexible enough so it will be practical to producers but not add undue risk." The proposed program allows Level 1-3 herds to purchase animals from non-program herds using individual animal testing. Level 4 herds may purchase from Level 2-3 herds in the same way. "The least risk of buying infection would be to purchase from a herd of equal or higher status level," Bulaga says.
Bulaga stresses that the purpose of the national program is to help support producers. The next phase for the working group will consist of implementing these recommendations, if approved by the USAHA Johne's committee and the USAHA Board of Directors.
The VJDHSP is one part of a complete Johne's program being developed by the NJWG for the U.S. Other parts of the program include a national educational effort, laboratory accreditation, and guidelines to assist infected herds.
Reprinted with permission from the Cattle Health Report—An LCI publication, Summer 1998