Ovine Johne's Disease - what you need to know

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OJD – an iceberg disease

Ovine Johne's Disease (OJD) is endemic across NSW after its detection on the Northern Tablelands in May 2023. While the infection was traditionally considered a southern disease, a number of cases across the Northern Tablelands have been diagnosed over the past 12 months. OJD is said to be an iceberg disease. For ever one animal showing signs of OJD another 25 most likely are sub clinically infected and show no signs. So that visibly impacted animal is the tip of the iceberg.

Ovine Johne’s disease (OJD) is an incurable, infectious wasting disease of sheep. OJD is caused by the sheep strain of the bacterium Mycobacterium paratuberculosis, which leads to the intestinal wall slowly thickening, causing reduced absorption of nutrients from the intestine. This eventually leads to severe loss of condition – infected sheep can waste away and die.

The bacteria are passed in the manure of infected animals, contaminating pasture and water supplies and spreading infection to other susceptible sheep. Once a flock is endemically infected with OJD, it is difficult to eradicate.

OJD is often not diagnosed in a flock until a significant proportion of the flock is already infected and deaths are occurring. There is often no sign for the first few years – that is why it is often referred to as a ‘silent but costly disease’. Infected sheep can be shedding the bacteria in their manure for a considerable period (sometimes years) even though the flock still looks healthy, but they are contaminating the pasture and infecting other sheep.

http://www.ojd.com.au/
http://www.ojd.com.au/publications/
OJD and Crohns
https://r.search.yahoo.com/_ylt=Awr933VrTJBkDE4ApAk36At.;_ylu=Y29sbwNncTEEcG9zAzIEdnRpZAMEc2VjA3Ny/RV=2/RE=1687207147/RO=10/RU=https%3a%2f%2fwww.foodstandards.gov.au%2fpublications%2fdocuments%2fedit_Report_JD%2520and%2520CD-%2520Final%2520Dec%25202004.pdf/RK=2/RS=NnhmukaeZ5y5g06X7280P2l6eXs-

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