Measures to combat Johne’s disease in Australia

Johne’s prevalence:

• Johne’s spread is varied from state to state across Australia

• Johne’s in sheep is a big issue and the disease is also found in dairy, beef (low prevalence), goats and red deer

• In the South, the disease is prevalent, the West is a free zone and the North a protected zone

• The country is split into different zones according to Johne’s disease prevalence in cattle:

1) Residual zones (Tazmania): Johne’s infection is endemic and no or minimal regulatory measures are enforced.

2) Control zones: Johne’s is present in this zone but it is a notifiable disease and there are control measures in place. There may be restrictions on movement of cattle into this zone from residual zones. Victoria is currently a Control Zone.

3) Protected zones are those areas where there is little or no evidence of Johne’s disease, there is a high level of confidence that if disease were present it would be detected; on-going surveillance is occurring and strict control measures are in place.

4) Free zones are areas where Johne’s disease is not known to exist. Western Australia is the only free zone. Considerable on-going surveillance is required to maintain a Free zone status, and immediate eradication of Johne’s disease is required if detected

Control programme

• A national Johne’s disease control programme has been running since the mid-nineties

• The disease is notifiable

• The programme is complex because of the varied distribution of the disease

• The aim is to protect areas that are not infected and reduce the impact of the disease and its effect on the environment in others

• Farmers need to know their situation and buy low risk animals

BJD Score:

• Calves are tested in some areas as part of an assurance scheme to reduce the risk of buying in infected cattle

• Herds are ranked on a scale of 0-10 by risk and calf rearing management

• This encourages farmers to buy from low-risk herds

• Farmers in a free zone would want to buy from a herd ranking 10 (A high score for assurance)

Johne’s disease calf accreditation programme (JDCAP):

• The “Three step Calf Plan” has been introduced nationally

• This includes, early separation of calves and not rearing in a contaminated environment

• By rearing calves under JDCAP, it is possible to add points on to your BJD Score

Example control strategies:

When Johne’s is detected in low level areas, such as Queensland:

• Detailed epidemiology and tracing carried out

• Test to assess risk to groups in herd

• May cull some groups and sometimes whole herd

• If a whole herd cull is needed, there is financial support for this in beef herd to try and maintain the low level of incidence in beef (0.04% infected herds in 2009). There may also be help for dairy herds in this position in a free or protected zone

When Johne’s is endemic, in areas such as the south-east of Australia:

• The aim is to reduce the effects of the disease

• Reduce spread of disease via calf rearing by carrying out best practice

The key to the programme’s success:

“We’ve made big gains from understanding how infection works and by moving away from a prescriptive programme to a risk assessment at individual farm level. Effective calf rearing has also been crucial,” says Mr Kennedy.

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