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Ovine Johne's Disease (OJD) is the description given to sheep suffering from a mycobacterium paratuberculosis infection. The symptoms are a general "wasting" of infected animals over a period of years. OJD is often mistaken for a range of other problems (abscess, worms, fluke, and dietary deficiency). OJD is known to be spread by ingestion of pasture contaminated with infected fecal matter, and is known to be spread by the transport of infected fecal matter in waterways. Young animals are more susceptible, and it appears that they can be infected by mother's milk. The bacterium has been reported to persist for longer than one year on the pasture.
Inter species transmission may mean that once Johnes disease has entered the local environment, it becomes virtually impossible to eradicate. This conclusion might be drawn when it is considered that Bovine Johne's Disease, although a strain distinct from OJD, can be carried by sheep, and by the report by Primary Industries and Resources South Australia (PIRSA) that: Interim laboratory results from veterinary research on Kangaroo Island have shown that two kangaroos and two wallabies have tested positive for the presence of Ovine Johne’s disease (OJD) bacteria.
With present technology it is not possible to reliably diagnose OJD in individual live sheep. Recent advances have reduced the unit cost and improved the accuracy of testing with a "pooled fecal culture" (PFC) test. If OJD is present the entire flock is assumed to be infected.
OJD in NSW AUSTRALIA Losses up to 9% have been reported in Australia. In NZ and other countries where the disease is endemic anecdotal evidence is that losses stabilize in the range 1% to 3% p/a. OJD was first detected in Australia circa 1980 in the central tablelands of NSW, and as of the end of 2000 there were 505 properties confirmed as infected in NSW. ( LAND p7, 26 April 2001).
The NSW Farmer's association has recommended (OJD
update May 03) that:
More than three years have passed since the Yass
RLPB suggested that reliance on market forces and vendor declarations
(backed by the Fair Trading Act) would best control the spread of
OJD. Two years ago it was suggested on these pages that
vaccine be provided on a commercial basis. We see here the
reluctance of government to unmake regulations.
Evidence suggests that mycobacterium paratuberculosis is present in our food and possibly in our water supplies. Alan Kennedy has uncovered and detailed research which would tend to make any normal hypochondriac like myself think seriously about giving up pasteurized milk products for life. His summary is particularly succinct.
The Veterinary Science faculty at the University of Wisconsin USA has published a page on the Zoonotic Potential of Johne's disease titled Association of M.paratuberculosis and Crohn's disease. Karen Meyer et al in the USA have collected and published very persuasive evidence on the site crohns.org.
More recent sites displaying research on the Johnes/Crohns link are the "paratuberculosis organization" site, whose sponsors offer membership for $50.00 US, and the Crohn's & Colitis Foundation of America who seek charitable (offline) donations.
Producer organizations continue to dither because, as they state:
"there is no evidence of a causative relationship".BUT
is not evidence of the lack of a causative relationship."
The evidence seems to indicate that pasteurizing (for 15 seconds at 72C) does not kill para, but that UHT milk and matured cheese are "safe". Matured cheese is thought to be safe because it's acidity kills the para bacterium over time. And perhaps well seared meat?
Created 1997, upgrades 14 November 1999, minor additions 1 January 2000, February 00, June 00, July 00. end 00 May 01