Disease Management

Johne's Disease is a notifiable disease in all States.

Owners of infected flocks have a responsibility to prevent the spread of the disease to clean flocks and properties.

This includes disclosing to prospective buyers the Johne's Disease status of any animals or land offered for sale. Failure to disclose this information could result in legal action by the purchaser of the sheep or land.

Sheep from infected properties must be sold directly for slaughter, to prevent the spread of Johne's Disease.

Johne's Disease usually enters a flock by introducing infected sheep (purchased from producers who do not realise their flock is infected) or stray animals (from infected neighbours). The chance of spreading infection via natural waterways is low but can occur.

Always ask for a written declaration from the vendor to ensure that Johne's Disease is not known or suspected to occur in their flock.

A vendor declaration is more meaningful if enhanced by evidence of on-farm testing to exclude the disease, either by blood tests, post-mortem examinations, or a combination of both. Such testing must be undertaken by a veterinarian approved for Ovine Johne’s Disease.

Sheep coming to South Australia from interstate must be accompanied by a Health Certificate (Form 2) to reduce the risk of OJD being introduced. These forms are available through offices of Primary Industries and Resources South Australia (PIRSA), equivalent government offices interstate, and most stock agents. The Health Certificates page on this website gives more details about restrictions and requirements for the movement of sheep and lambs.

The best assurance comes from participation in the Australian Sheep Market Assurance Program (SHEEPMAP).

Keeping boundary fences in good condition is also a sound management practice.

Vaccination

Vaccination can form part of the disease management strategy. The section on Vaccination (.PDF) 68KB explains vaccinating against OJD, details about Gudair vaccine, what you need to do if you want to vaccinate, the benefits of vaccination and OH&S issues.

Eradication

This strategy involves destocking all infected sheep from the property, leaving it free of sheep for at least 15 months (including two summers), then re-stocking with clean sheep.

In South Australia, this is currently the only permissible strategy for control of Ovine Johne's Disease (OJD).

During the destocked period, farm income could be generated by cropping, by running cattle or by running sheep destined for slaughter within six months of exposure.

Embryo Transfer Programs

This may be an option for stud flocks that destock but wish to retain the genetic base of their flock. Special embryo washing and processing procedures can prevent transmission of Johne's Disease by embryo transfer.

Other options

Do nothing

In New Zealand and New South Wales, where the disease is more common, owners of commercial flocks with a low level of disease may choose to live with the disease in their flock, only selling sheep for slaughter. This option is not acceptable in South Australia.

Management changes

The economic impact of the disease in a flock can be reduced by culling sheep at a younger age and purchasing 'clean' adult sheep, such as first cross ewes. Sheep must be culled direct for slaughter to prevent further spread of the disease.

Test and cull programs

Current blood and faecal culture tests fail to detect all infected sheep. This means that test and cull programs are unlikely to be successful in controlling the disease. This option is not acceptable in South Australia.

Vaccination

Vaccination against Johne's Disease in sheep is practised in some overseas countries. Because it only reduces the clinical effects rather than prevent infection, the vaccine is currently not available for use in South Australia.