Johne's disease, or JD, is a chronic and incurable bacterialinfection of the lower intestinal tract of ruminant animals. Most commonlya disease of cattle, sheep and goats, it can infect any ruminant includingdeer, elk, bison, llamas and alpacas. The vast majority of infected animalsappear completely normal although many of them are already shedding theorganism and are therefore infectious to others. The clinical signs, whichare weight loss and diarrhea, generally do not appear until animals are in themost advanced stage of the disease. The time from first becoming infecteduntil development of clinical signs is often two or more years.
Johne's disease is spread by ingestion of the organism which isshed in the manure and sometimes also the milk of an infected animal.Susceptibility to infection is greatest in young animals - the youngerthe animal the greater the susceptibility. The most effective managementprincipal in reducing the infection rate in a herd is to prevent the exposureof young stock to adult animals, their milk and their manure.
The Bureau of Animal Health and Diagnostic Services, incollaboration with USDA, has developed several voluntary programs designed toaid herds in their efforts to detect, reduce infection rates, and/or preventthe introduction of Johne's disease.
PA Johne's Herd Certification
The Pennsylvania Johne'sdisease Herd Certification Process provides a structured framework whichveterinarians, herd owners and herd managers can use to develop a meaningfulherd management plan. Herds that develop and implement such a plan can
be recognized for their participation by being classified as a "Management"or “Testing and Classification” herd.
The Management Option is designed for herds thatwould like to use management changes to minimize the risk of Johne's diseaseentering or spreading within the herd, but do not wish to participate in regular testing of itsanimals for Johne's disease. Both infected and uninfected herds may enroll inthis level. No claims concerning the level of JD in the herd can be made byherds participating at the Management Level since no structured diagnostictesting is carried out. Herd owners have the option of adding some level of strategicdiagnostic testing to their management protocol if they and their veterinariandecide that it would benefit their ability to assess the level of infection inthe herd and/or to monitor the prevalence of disease over time in response tomanagement changes which are instituted.
THETESTING and CLASSIFICATION Optionis for herds that have not had any recent evidence of Johne's disease or wish,through regular testing and management changes, to eventually eliminate thedisease from the herd. Herds in thisoption, through prescribed testing methods, can document the level of infectionin the herd and work to reduce the infection rate over time with the ultimategoal of demonstrating that the herd has become free of Johne’s Disease. This option consists of utilizing managementchanges and annual testing protocols determined by the size of the herd tofirst evaluate the level of infection and then work to reduce it. There are six levels in this option withlevel ONE herds having the highest rates of infection and levels Four throughSIX limited to herds with no test positive animals. Although level six herds have had at leastthree years of all negative test results, the nature of Johne’s disease is suchthat they cannot be considered free of infection. And, in fact, most scientistsagree that once infected, few herds can ever again be declared to beunequivocally free of Johne's disease.
In order to participate in the PA Johne's Herd CertificationProcess, interested herd owners must work with a Johne's Certified Veterinarianto complete an enrollment application and carry out a risk assessment in orderto develop a herd management plan. The application must be completed andsubmitted to the Department along with the Johne's disease Risk Assessment andHerd Management Plan for Dairy or Beef herds. Further details regardingparticipation at each level, and more information regarding the PA Johne's HerdCertification Process can be found at the following website: http://www.johnesdisease.org.
Johnes Certification for Veterinarians
Veterinarians wishing to become Certified toparticipate in Pennsylvania’s Voluntary Bovine Johne’s Disease CertificationProgram should contact Dr. David Griswold, PA Department of Agriculture, at717-705-1626 or at firstname.lastname@example.org. Certified veterinariansmust renew their recertification every five years.
Recertification trainingwill become available online in early 2012.
GOATS and SHEEP
While Pennsylvania’sprogram is designed for cattle, the decision has been made to offer aManagement option program to sheep and goat producers who are interested inaddressing Johne’s disease in their flocks and herds. This program is available to producers whoare willing to adopt the risk assessment/herd management format utilized bybeef and dairy herds. In order to beconsidered for the program, the producer must work with a PA Johne’s Certifiedveterinarian, enroll in the program and follow the best management practiceguidelines outlined in the beef and dairy management handbooks, but with theappropriate species alterations. Participating herds and flocks will qualify for the same reducedlaboratory testing fees offered to enrolled cattle herds.
The Testing andClassification option is not available to sheep flocks and goat herds becausethe model it employs was designed around the epidemiology of the disease incattle. That same model cannot beapplied to the disease in small ruminants. If such a model is developed in the future, Pennsylvania will consideroffering a Testing and Classification option for sheep and goats as well.
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