Cattle that do not develop clinical Johne's disease DO NOT recover and will die from inability to absorb nutrients and fluids from the intestinal tract.
Prevalence
Johne's disease was identified more than a century ago and remains a common and costly disease. Widely distributed throughout the world and across all regions of the United States, Johne's is also a recognized problem in North Carolina herds.
Economic Impact
According to the National Animal Health Monitoring System (NAHMS), in test-positive herds with at least 10% of animals culled in the past year with clinical signs of Johne's , the disease costs dairy producers more than $200 per cow annually (or over $20,000 in a 100 cow dairy). These losses are primarily due to decreased milk production and premature culling.
Although the economic impact to beef herds is more difficult to measure, these losses can be substantial. Losses result from decreased performance, premature culling and the costs associated with testing for the disease. The beef industry also suffers economic losses from decreased production life and reduced slaughter weights of salvageable animals. Additionally, the sale of breeding stock with Johne's Disease increases liability. As buyers become more aware of the disease, they may demand to know the Johne's status of breeding stock they buy.
Diagnosis
Diagnosing Johne's disease can be quite difficult due to subclinical infections that may not become apparent until years later. For each clinically affected animal, there are potentially 15 to 25 other animals that are subclinically affected. This is termed, "The Iceberg Phenomenon."
Animals can be blood tested for antibodies to the disease and a fecal culture can be taken to determine if an animal is positive or suspect for Johne's. Initial symptoms usually appear following stress, such as calving or poor nutritional management, and are often confused with parasitism.
Awareness
Recent surveys conducted by NAHMS indicate more than 92% of beef producers and 45% of dairy producers are unfamiliar with the disease. Thus, there is a tremendous need for producer education and control programs regarding Johne's Disease.
Similarities exist between Johne's Disease and Crohn's Disease, a chronic intestinal disease in humans. Current studies using sound epidemiologic principles have not established an association between human contact with Johne's infected animals and Crohn's Disease. Research is ongoing in this area.
Prevention and Control
Since the primary route of transmission within a herd is fecal contamination, biosecurity measures aimed at reducing or eliminating calf exposure to infected feces are the most powerful tools available.
Currently, there is no proven, effective treatment and NO CURE for Johne's disease. However, the disease can be both controlled and prevented:
There is no approved vaccine for use in cattle or small ruminants in North Carolina.
In order to control this disease, environmental contamination and exposure to the organism must be reduced, especially in young calves, lambs and kids. Manure from infected adults should be applied only on cropland to be tilled. Young stock must be isolated from contaminated barnyards, pastures and water. In identified Johne's infected herds, youngstock (primarily dairy calves) must be removed from dams immediately after birth.
Johne's Disease Risk Control Points*
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Risk Decrease
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Risk Increase
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Fetus
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+ Uninfected dam
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- Infected dam Clinical/Subclinical
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Newborn
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+ Clean, dry environment
+ Colostrum via negative dam
+ Immediate isolation
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- Colostrum pooled
- Dirty multi-use environment
- Nursing allowed
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Pre-wean
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+ Milk/replacer from negative animals
+ Not exposed to adult manure
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- Milk from suspect/infected dams
- Exposed to adult manure
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Weaned
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+ Fresh feed
+ Not exposed to adults
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- Exposed to adult manure
- Fed feed left by adults
- Common feed/manure equipment
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Breeding
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+ Fresh feed
+ Not exposed to adults
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- Fed feed left by adults
- Common feed/manure equipment
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Lactating
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- Fed feed left by adults
- Common feed/manure equipment
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*Risk control points are manageable activities that minimize the introduction and/or spread of infectious disease.
Organized Johne's Control Program
A statewide Johne's Advisory Committee has been appointed by the North Carolina Department of Agriculture and Consumer Services. This committee will work to improve awareness of Johne's Disease and establish a voluntary Johne's Disease Control program in line with guidelines established by the National Johne's Working Group.
Summary
Johne's disease, a chronic debilitating intestinal disease in cattle and other ruminants, can potentially result in substantial production and economic losses. Diagnosis is difficult since animals that demonstrate clinical signs are only a tiny fraction of the total number of animals infected. There is no effective treatment for this disease. Management is vital for herd prevention and control. Increased awareness and knowledge of this disease is critical for progress to be made in reducing the spread and economic liability created by Johne's Disease.
Acknowledgements
Partial funding for this brochure was provided by a North Carolina State University, Faculty Outreach and Professional Development Grant. This brochure was created by Dr. Barrett Slenning, Department of Farm Animal Health and Resource Management (FAHRM), College of Veterinary Medicine, North Carolina State University. Assistance was provided by the following FAHRM ruminant faculty: Dr. Kevin Anderson, Dr. Allen Cannedy, Dr. Peter Farin, Dr. Elaine Hunt and Dr. Wayne Oxender.
