Johne’s disease is a reportable animal disease under Western Australian legislation. The presence or suspicion of this disease must be reported to the Department of Primary Industries and Regional Development (DPIRD) as soon as possible.
During office hours, contact your nearest DPIRD field veterinary officer - see the Livestock Biosecurity contacts webpage.
After hours, contact the exotic animal disease toll-free hotline on
What causes JD?
JD is caused by the bacteria Mycobacterium paratuberculosis. There are several strains of the bacteria, including sheep, cattle and bison strains. These strains are not specific to cattle and can infect sheep, goats, alpaca and deer as well.
The bacteria live and multiply in the lymph nodes and the small intestine of the animal and cause the intestinal wall to thicken. This reduces the animal’s ability to absorb food and water and results in continuing weight loss and death.
Signs of JD in cattle
JD has a long incubation period. Typically, cattle are most likely infected as calves and will not show any signs of illness until they are 3-4 years old. However, JD can cause reduced production levels even before the animal is noticeably unwell and the animal can be spreading the disease.
The visible signs of JD in cattle are:
- chronic diarrhoea that does not respond to treatment
- gradual weight loss despite normal or increased appetite with ample feed.
The signs of JD in infected animals are often triggered by stress factors such as calving, producing milk and a lack of feed or poor feed. Infected animals die within a few weeks to several months after the onset of signs.
How is JD spread?
JD can be spread among livestock through ingestion of the bacteria present in the colostrum, milk and faeces of infected animals or ingestion of soil, feed or water contaminated by the bacteria.
The bacteria can survive in the soil for up to 12 months under cool, moist conditions.
Calves are most likely infected by suckling udders that have been contaminated with infected faeces. They can also be infected by drinking infected colostrum or milk or grazing contaminated pasture or feed. In cattle with visible disease, calves may also be infected in-utero.
Cattle can also be infected through contact with sheep, goats, alpaca or deer infected with JD or by grazing land grazed by infected animals.
Which animals are most at risk?
Calves are most susceptible up to 30 days old and remain at risk until around 12 months old.
Cattle over 12 months old are relatively resistant and, if they do become infected, are very unlikely to develop signs of disease or shed enough bacteria in their faeces to spread the disease.
How do we test for JD?
Several tests are available for JD, but all have limitations.
- blood tests – which look for an immune response to infection
- faecal tests – looking for bacteria in the faeces by culture or finding bacterial DNA
- postmortem tests – looking for bacteria in the gut and lymph nodes under a microscope, or finding bacteria by culture or bacterial DNA.
Testing for JD is complex and takes time. Blood testing is not very specific and is likely to give some false positives (give a positive result even if there is no disease). It is a useful screening tool, but is not used for definitive diagnosis.
Testing faeces of live cattle is not very sensitive as it will only detect infection in animals already shedding bacteria. It is better used as a herd test rather than on individual animals. Young animals will test negative even if they are infected.
Finding JD in dead cattle involves looking at gut and lymph nodes under the microscope and finding the bacteria in faeces and tissue samples. This is the most sensitive method for finding disease in an individual animal, but will not pick up all infections especially in young animals. It takes more than three months to obtain results from culture of tissues or faeces.
Whenever a positive test is received, further testing by histology or culture is carried out to confirm the diagnosis.
For details of testing and sampling requirements, refer to Animal Health Australia’s (AHA) website.
What is the economic impact of JD in cattle?
A number of export markets place JD conditions on cattle and cattle products.
In dairy herds, JD causes economic losses through reduced milk production, reduced conception rates and restrictions on trading. In beef herds, the economic impact is still present but less significant, especially in well managed herds.
The level of infection in a herd increases over time and if the disease is left unmanaged, the economic effect of JD becomes increasingly significant.
How is JD in cattle managed in Australia?
A new national framework for JD in cattle was implemented on 1 July 2016. Under the new framework, if JD is diagnosed, it must be reported to state or territory agricultural authorities. It is not regulated at a national level, however it is still regulated in WA. Producers are encouraged to manage the risk of JD occurring on their property by using biosecurity tools such as the market assurance schemes Johne’s Beef Assurance Score (J-BAS) and Dairy Score and implementing farm biosecurity plans.
More information on the new approach to JD in cattle and biosecurity tools to manage the risk of JD can be found on the AHA website. The Department website also has a J-BAS factsheet and flowchart tailored for WA producers.
Regulation of and surveillance for JD in cattle in WA
JD in cattle is not known to be present in WA, which provides some trading advantages. The WA cattle industry has decided to continue to regulate the management of JD in cattle and to maintain border controls for JD. This decision was informed by an economic assessment of the potential costs of JD in cattle within WA should it enter and become established. The report is available on the Department website – search Economic impact evaluation of bovine Johne’s disease.
A targeted surveillance program was commenced in September 2017 to support this decision and will be completed over the next 12 months. For the results of the targeted surveillance program to date, see the Documents link at right.
The conditions for cattle entering WA can be found on the Department website in the LB1 form - Health certificate for movement of stock to Western Australia.
Note that JD in cattle is still a reportable disease in WA. If JD is suspected or diagnosed in your cattle, you must report it to the Department.