Managing Johne's disease in sheep on infected properties
The Ovine Johne’s Disease management program is supported and funded by the SA Sheep Advisory Group (SASAG) through the Sheep Industry Fund.
Procedure for managing OJD on infected properties
The following procedure may be followed to guide responses to the detection of Ovine Johne’s Disease (OJD) on a property either through voluntary abattoir surveillance or disease investigation:
- Post mortem findings confirmed by laboratory testing of gastrointestinal tract samples and/or pooled faecal testing of a screening test High Throughput – Johne's PCR (HT-J PCR) on high risk mobs of sheep on the property.
- If Johne's DNA is detected in the HT-J PCR screening test a bacterial culture is performed to isolate and grow the bacterium to confirm the disease status. The bacterial culture takes 12-16 weeks before results are available.
- A Property Disease Management Plan (PDMP) can be developed by producers through PIRSA’s One Biosecurity program to manage the risk of disease spread and economic losses. Orders under the Livestock Act 1997 may be placed on the property if producers fail to undertake reasonable measures to manage OJD and risks to industry.
- The PMDP will detail a timeline to manage the disease and a best practice vaccination plan, strategic grazing and trading practices.
- Direct neighbours of infected properties are considered at risk. As part of meeting their biosecurity obligations to reduce the risk of OJD to industry infected producers should notify their neighbours and other producers they have sold stock to of the change to their OJD status. When a producer chooses to notify their neighbours or producers they have sold stock to, then PIRSA can provide support by talking to individual producers and/or hold community meetings to provide advice on undertaking risk assessment and best practice disease management. Upon written request from the infected producer, PIRSA can undertake notification on their behalf.
- Best practice trading options for infected properties may include:
- direct sale for terminal slaughter at abattoirs
- direct sale for feedlots
- approved vaccinates
- interstate (producers must check the entry requirements for livestock to that state)
- all sheep must be accompanied by a National Sheep Health Declaration indicating the suspect or infected status of the flock.
- A property will be considered low risk once:
- all sheep on property to be retained until greater than 18 months of age are approved vaccinates.
- Properties wishing to achieve an 'uninfected'/'undetected status' will need to undertake a clearance test or destocking program:
- the property can undergo a clearance test a minimum of 2 years after the last detected infected animal has been destocked and sheep are approved vaccinates - a successful clearance test is when the JD bacteria is no longer detectable on a Pooled Faecal 350
- a destocking program approved by the Chief Veterinary Officer has been completed.
- Time frame for properties to reach a low risk or undetectable status will depend upon:
- length of time breeding ewes and their ewe progeny (from initial disease detection) are retained in the flock - each cast for age will result in a corresponding delay in the clearance testing date
- delays also occur when replacement sheep purchased are not approved vaccinates.
Vaccination to minimise OJD risk
The Gudair vaccine is available from most agricultural suppliers. It should be used as a preventative risk management tool rather than waiting until suspicion or detection of disease occurs.
Producers in high risk areas or with high risk businesses should consider incorporating Gudair vaccine in their regular animal health program as they do with other vaccines and intestinal parasite treatments to prevent disease occurring.