Regulatory controls for Johne's disease (JD) in cattle in Western Australia

JD is JD, whatever the species or the strain

JD is defined nationally and internationally as infection with any strain of Mycobacterium avium subsp. paratuberculosis, which includes sheep (S-strain), cattle (C-strain) and bison (B-strain). These strains can affect more than one species, not just the strain they are named for.

Export markets require certification of JD and do not differentiate between the strains of JD that caused the disease. Detection of any strain of JD in any livestock species is considered JD. JD in cattle is commonly referred to as bovine JD (BJD) and in sheep as ovine JD (OJD).

History of JD in cattle regulation

Following national consultation, JD in cattle was deregulated in all Australian jurisdictions in 2016, except Western Australia. The national framework for responding to JD in cattle was discontinued as despite affected jurisdictions attempting to eradicate JD for many years, it had continued to spread, with the continuing regulation imposing significant financial and social impacts that were greater than those of the disease.

As a result of this national decision, the Australian Johne’s Disease Market Assurance Program for Cattle (CattleMAP) ceased. This meant JD zones under CattleMAP no longer applied and WA was no longer recognised as a free zone.

With these changes to national management of JD in cattle and the cessation of CattleMAP, voluntary risk-profiling industry assurance schemes were initiated in 2016 to assist producers to mitigate risk at a property level. Due to WA’s previous BJD free zone status before national deregulation, WA beef cattle producers were given an interim Johne’s Beef Assurance Score (JBAS) of 8, provided they did not have a history of JD in any species, had completed a property biosecurity plan signed by a veterinarian by 1 July 2017 and had undertaken a faecal check test by 30 June 2018.

Following the national decision, the WA cattle industry requested the Department of Primary Industries and Regional Development (DPIRD) maintain regulation for JD (C-strain) as C-strain had not been detected in WA cattle at that time. If JD C-strain was detected, any regulatory actions would be determined by an assessment of the situation and subject to industry consultation. To support the request for maintenance of regulation, targeted surveillance was carried out in 2017/18, which demonstrated the negligible prevalence of JD (C-strain) in WA cattle herds. Following this surveillance, WA industry requested and DPIRD agreed to enhance import regulations to reduce the likelihood of JD C-strain being introduced into WA.

Confirmation of JD C-strain in WA in 2021

In September 2021, JD C-strain was confirmed in homebred cattle on a property in southern WA.

DPIRD carried out a comprehensive investigation of the detection of JD (C-strain) that showed JD had been present for several years and numerous cattle had been moved off the property to multiple WA properties during that time. Only a small number of the moved cattle are expected to be infected. The investigation was unable to determine the original source of JD C-strain, which may have come from another WA property.

Given the long incubation period and the number of cattle and length of time it would take for testing to detect JD in the likely small number of infected cattle among the large number of impacted properties, attempting eradication would result in a significant economic cost to industry. If eradication was attempted, large numbers of WA cattle properties would be placed under regulatory controls for up to five years during surveillance to determine if the disease was present on their properties. The social and financial impacts would outweigh the impact of the disease itself.

Following the investigation, industry and government met and determined that eradication of Mycobacterium avium subsp. paratuberculosis (C-strain) was not technically or economically feasible and agreed to align with the national approach to JD.

What JD regulation will stay the same:

• Under the Biosecurity and Agriculture Management Act 2007 (BAM Act), the detection of any strain of JD in any species in WA must continue to be reported, in order to support certification for live export markets. As a reportable disease, anyone with a suspicion or detection of JD in livestock must report it to a BAM Act authorised inspector, such as a DPIRD Field Veterinary Officer [1], as soon as possible.

What JD regulation will change:

• DPIRD will no longer apply disease regulatory instruments to properties found to have JD C-strain. This means DPIRD will not require destocking of properties where an animal with JD (C-strain) has been identified. This aligns with the national decision to deregulate JD in cattle in 2016 and is how WA already manages S-strain in cattle and any strain of JD in sheep.
• The WA Chief Veterinary Officer will work with relevant third parties to seek the approval of the Australian Pesticides and Veterinary Medicines Authority for registration of the Silirum vaccine for use by veterinarians in WA.
• DPIRD and the WA cattle industry have agreed on the need to amend WA's import conditions to reflect the reduced regulation of JD in WA. These amended import conditions for all JD-susceptible livestock will come into effect on 17 January 2022. The current import conditions continue to apply until this date. For more information, see the webpage: Forms for importing livestock [2].

Support for producers to manage these changes

To enable producers to apply risk mitigation measures appropriate for their business, DPIRD will support WA industry with information on the disease, on-farm biosecurity practices and the national industry assurance programs.

For more details, see the webpages:

• JD in cattle: management in WA [3]
• FAQs: JD in cattle in WA [4]