Johne's disease (JD) in livestock
What is Johne’s disease (JD)?
Johne’s disease (JD) is a chronic, incurable infectious disease that affects cattle, buffalo, sheep, goats, alpaca and deer. It is caused by the bacteria Mycobacterium avium subsp. paratuberculosis. The disease causes progressive diarrhoea, weight loss, reduced production levels and eventually death.
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. JD in cattle is commonly referred to as bovine JD (BJD) and in sheep as ovine JD (OJD).
What disease signs do livestock with JD show?
Cattle are infected when they are very young but do not show any signs of disease until they are much older, usually after 3-5 years of age. After this age, the most common signs of disease include progressive diarrhoea, weight loss, reduced production levels and eventually death.
How can JD be detected in livestock?
Although livestock are infected when they are very young, they are not infective (capable of spreading the disease) nor do they show signs of disease until they are much older, usually after 3–5 years of age. Several tests are available for JD, but each has limitations which need to be taken into account by the testing veterinarian. Refer to the webpage Johne’s disease in cattle: management in WA for further information.
How is JD introduced onto a property?
The most common way a property will become infected with JD is by introducing infected livestock that are not showing any signs of disease. See How are livestock infected with JD for further information.
How are livestock infected with JD?
JD can be spread between livestock through:
- faeces of infected animals, infected or contaminated colostrum and milk or
- soil, feed or water contaminated by the bacteria. The bacteria can survive in the environment for long periods, including in soil for up to 12 months.
Young animals, under 12 months, are most susceptible to becoming infected. They can be infected by grazing contaminated pasture or feed, or by suckling from udders contaminated by faeces. They can also be infected by drinking infected or contaminated colostrum or milk. In pregnant livestock with visible disease, their offspring may become infected in utero (prior to birth).
Any susceptible livestock can be infected through contact with faecal contamination from another susceptible species whether cattle, sheep, goats, alpaca, deer or buffalo infected with JD or by grazing land grazed by other infected livestock.
While animals are usually infected early in life, they do not shed the bacteria for a number of years. They are not infective to other animals until they start to shed the bacteria in their faeces. This is important in managing the disease on a property.
JD regulation in WA
What strains of JD are present in WA?
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. JD in cattle is commonly referred to as bovine JD (BJD) and in sheep as ovine JD (OJD).
JD (S-strain) is endemic in sheep in WA and S-strain has been detected in cattle in WA.
JD (C-strain) was confirmed in homebred cattle in southern Western Australia in September 2021. DPIRD carried out a comprehensive investigation that showed that JD C-strain 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.
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, as soon as possible
Why was JD C-strain not eradicated when it was detected in September 2021?
JD (C-strain) was confirmed in homebred cattle in southern Western Australia in September 2021. DPIRD carried out a comprehensive investigation of the detection of JD (C-strain) that showed that it 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.
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, as soon as possible.
Following the C-strain detection, what regulations now apply to JD in cattle in WA?
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, as soon as possible.
DPIRD’s management of JD (C-strain) detections will align with the national decision to deregulate JD in cattle in 2016 and with the current management of detections of S-strain in cattle and any strain of JD in sheep in WA.
The WA Chief Veterinary Officer will work with relevant third parties to seek the approval of the Australian Pesticides and Veterinary Medicines Authority (APVMA) for registration of the Silirum vaccine for use in WA.
DPIRD and WA industry have agreed on the need to amend WA's JD 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. Until this date, the current import conditions continue to apply.
Please refer to the webpage: Forms for importing livestock into WA for more information on the import conditions.
Read more about the history of JD regulation on the webpage: Regulatory controls for Johne’s disease in cattle in WA.
What happened to CattleMAP?
As a result of the national decision in 2016 to deregulate management of JD in cattle, the Australian Johne’s Disease Market Assurance Program for Cattle (CattleMAP) ceased. This meant that officially recognised JD zones under CattleMAP were no longer recognised and WA was no longer a free zone.
With national deregulation 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.
What do I do if my cattle have signs consistent with JD?
Producers should call a private or government veterinarian to investigate if they see disease signs that look like JD, as JD remains a reportable disease. Calling a vet is recommended as early detection will help you to manage the disease more effectively and reduce the risk of further spread. DPIRD subsidised disease investigations and testing are available where JD is suspected. Please contact your private vet or DPIRD Field Veterinary Officer.
Testing for JD
How can JD be detected in livestock?
Although livestock are infected when they are very young, they are not infective (capable of spreading the disease) nor do they show signs of disease until they are much older, usually after 3–5 years of age. Several tests are available for JD, but each has limitations which need to be taken into account by the testing veterinarian. Refer to the webpage Johne’s disease in cattle: management in WA for further information.
How can I detect JD on my property?
A history of laboratory testing for JD on a property is an important part of determining the likelihood of JD being present on the property. Although infection generally occurs in the first 12 months of life, JD has a long incubation period and can only be detected by laboratory testing once the animal is shedding the bacteria, which usually occurs after 3–5 years of age. Periodic testing of a large and representative number of homebred livestock over four years of age provides the most accurate way to determine the presence or absence of JD on your property.
The consequence of an introduction, if it occurs, can also be reduced by early detection through regular JD testing and veterinary investigations of scouring or ill-thrifty livestock. Producers who suspect they have livestock with JD may be eligible for subsidised investigation through the Significant Disease Investigation (SDI) program.
Refer to the webpage Johne’s disease in cattle: management in WA for further information to assist with biosecurity planning.
Why might faecal testing of individual or small numbers of livestock not detect JD in infected cattle?
Young animals do not shed the bacteria until later in life, so testing young animals will not detect the disease. Additionally older animals may shed the bacteria intermittently and produce a false negative result, even though they are infected. This means that faecal testing for JD should be undertaken on a representative herd level, involving testing large numbers of homebred cattle over four years of age, rather than an individual level. A property that has negative herd-level laboratory tests over a number of years has a higher confidence of freedom from the disease.
Regular and repeated herd faecal testing of livestock of an age that are likely to be shedding is important to detect the disease early before it spreads within the property.
Managing a JD detection
What do I need to consider if JD is detected on my property?
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, as soon as possible.
DPIRD’s management of JD (C-strain) detections will align with the national decision to deregulate JD in cattle in 2016 and with the current management of detections of S-strain in cattle and any strain of JD in sheep in WA.
The production impact that the presence of JD will have on a property depends on the enterprise. Producers should discuss their individual operation with their veterinarian to determine the impact JD would have on their property and the mitigations that should be implemented.
Producers should note that JD can make the property ineligible to supply livestock to live export markets with JD import conditions. For more information, see the Johne's disease management webpage Trade and market access section. Please contact DPIRD at livestockbiosecurity@dpird.wa.gov.au for queries on property eligibility requirements.
There may also be an impact on the Johne’s Beef Assurance Score (PDF download) and Johne’s Disease Dairy Score status, which may need to be considered for domestic trade.
Biosecurity planning for JD
How can producers plan their biosecurity for JD risk?
Given that it may be several years between the time of infection and livestock being capable of spreading the disease or showing signs of disease, there are three key factors WA producers should consider when undertaking JD biosecurity planning. These are:
- the impact of JD on the individual property
- the likelihood that JD will be introduced onto the property and
- property-level risk mitigation strategies in place.
Refer to the webpage Johne’s disease in cattle: management in WA for further information on biosecurity planning.
What strategies should producers consider on their property to reduce their risk or impact of JD infection?
Producers should take the following strategies into account to reduce their risk or impact of JD infection:
- industry assurance programs/risk-profiling tools, such as Johne’s Beef Assurance Score (JBAS), Johne’s Disease Dairy Score (JDDS) and other market assurance programs.
- biosecurity plans and biosecurity checklists
- National Health Statements
- grazing management, including avoiding co-grazing with other susceptible species or grazing on land previously grazed by unknown status or infected livestock
- herd-level faecal testing
- vaccination and
- calf-rearing programs as relevant to the property/enterprise.
Refer to the webpage Johne’s disease in cattle: management in WA for further information on biosecurity planning.
Why should producers have a biosecurity plan?
Developing and maintaining a farm biosecurity plan will assist with the identification and management of risks to your business from JD. It should include decisions regarding herd introductions of all susceptible species, co-grazing with species susceptible to JD, testing and vaccination.
Refer to the webpage Johne’s disease in cattle: management in WA for further information on biosecurity planning.
What should producers consider when selecting livestock to introduce onto their property?
Livestock can be infected without showing any signs of disease. Producers should consider the geographical location of the supplying property and livestock introductions onto the supplying property before introducing livestock.
Sourcing livestock from closed herds or herds with minimal introductions and with a history of testing on the property can help to reduce the likelihood of JD introduction. Properties which have sourced susceptible livestock from properties with no testing history or from an area of high JD prevalence are at higher likelihood of disease.
The supplying property JD vaccination history should be considered. Vaccination can be used on properties which do not have JD to reduce the likelihood of disease introduction onto property, or in response to disease detection on property.
Testing of only the livestock to be introduced onto your property provides some assurance of their JD status, provided they are old enough to test. Testing of the supplying property provides a more accurate indication of the introduced livestock status. This is because large numbers of livestock need to be sampled to be confident the test will detect disease if present.
Refer to the webpage Johne’s disease in cattle: management in WA for further information to assist with biosecurity planning and identifying lower risk introductions.
Why should I ask for a National Health Declaration when buying livestock?
Producers are encouraged to ask for a National Health Declaration when buying livestock. This contains the biosecurity and health information of the supplying property and livestock and provides greater confidence of the JD status of a property.
What are JBAS and JDDS?
The Johne’s Beef Assurance Score (JBAS) (PDF download) and Johne’s Disease Dairy Score (JDDS) are voluntary risk-profiling tools for their respective industries. Properties with a higher score are considered less likely to have JD. However, the scores are a guide only and should be used in conjunction with other biosecurity practices to minimise the risk of introducing JD onto your property.
Vaccination
Will using Silirum vaccine protect my property?
The vaccine is not currently registered for use in WA. DPIRD will advise when the legislative requirements for the supply of the vaccine are finalised. For more information, see the webpage: Johne’s disease in cattle: management in WA.
Vaccination of cattle with Silirum may be a useful tool to minimise potential spread of infection, particularly when introducing cattle or in herds where a diagnosis of JD has been confirmed or is unknown. Silirum is an inactivated (killed) vaccine that may not prevent infection but can significantly reduce its spread. Vaccination is most effective when given to calves between three and six weeks of age, however, vaccination of cattle older than this may reduce shedding if vaccinated animals subsequently become infected. Vaccination should be used as a tool to complement on-farm disease management practices and as a part of a general farm biosecurity plan to minimise the risk and impact of JD.
Can I use Silirum vaccine if I export my cattle?
Producers who plan to use Silirum should note this may affect their eligibility to provide vaccinated cattle for export if the importing country has JD or tuberculosis requirements, as the vaccine can cause (false) positive results for both JD and tuberculosis tests.
Vaccinated cattle must be identified in accordance with vaccine label instructions, which require identification of the vaccinated animal with a three-hole punch, preferably in the outer third of the right ear. The person administering the vaccine must ensure vaccinated animals are recorded in the National Livestock Identification System (NLIS) database as JD vaccinates. For more information, see the webpage Johne's disease in cattle: management in WA Trade and market access section.
Where can I find more information?
For further information, contact your private veterinarian or DPIRD field veterinary officer or visit the following webpages: