What is OJD?
Note Number: AG1126
Published: October 2003
Updated: November 2009
Ovine Johnes (pronounced yoh-nees) disease is a fatal, wasting disease of sheep. Ovine Johnes 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.
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 ewes 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
Acknowledgements
This note was developed by Mike Jeffers. October 2003.
It was reviewed by Mike Jeffers, Animal health Field Services. November 2009.
ISSN 1329-8062
Published and Authorised by:
Department of Primary Industries
1 Spring Street
Melbourne, Victoria
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