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Ovine Johne’s (pronounced ‘yoh-nees’) disease is a fatal, wasting disease of sheep. Ovine Johne’s disease is often abbreviated to OJD.
What causes OJD?
OJD is caused by infection with one or more strains of the bacteria, Mycobacterium paratuberculosis.
What are the signs of OJD?
OJD is a chronic infection of the bowel. This causes the lining of the bowel to thicken and reduces the absorption of food. Affected sheep show severe wasting. Chronic scouring may occur. Sheep will eat and drink normally until they are too weak to graze. Death is inevitable.
The average time from onset of illness to death is six weeks to three months.
The classic sign of the disease in a sheep flock is a distinct ‘tail’ to the mob, comprising sheep in uncharacteristically poor condition.
Most sheep do not show signs of illness for a long time after infection. Many sheep infected with the bacteria may carry the bacteria in the gut and spread the disease without showing any obvious signs.
A sheep showing signs of OJD.
How are sheep infected with OJD?
Sheep can become infected at any age, however young sheep are more susceptible. Susceptibility can also be influenced by breed, stress and the presence of other diseases.
Infected sheep shed bacteria in their manure and contaminate the environment before showing signs of OJD. Other sheep become infected when they consume food or water contaminated with this manure. The OJD bacteria can survive twelve months or more in a favourable environment, such as sheep campsites and swampy or wetter areas of the farm.
Lambs can also become infected while in the ewe’s uterus. However, this usually occurs only if the ewe is showing signs of OJD.
What is the treatment for OJD?
While there is no treatment for OJD, vaccination against this disease is proving to be highly effective at decreasing death rates of sheep, reducing the number of sheep shedding bacteria, and reducing the number of bacteria shed in the manure of those infected sheep that shed bacteria.
OJD and other species
OJD can also affect goats and deer (other than fallow deer).
Further information
Further information about OJD can be obtained from animal health staff at your nearest DPI office or on the DPI web site: http://www.dpi.vic.gov.au/farming/OJD
The previous version of this note was published in October 2003.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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