Bovine Johne’s Disease (BJD)
NT Fact Sheet last updated: 17 December 2012
What is Johne’s Disease
Johne's disease (JD) is a serious wasting disease of cattle, sheep, goats, alpaca, llama, camels
and deer caused by the bacteria Mycobacterium avium paratuberculosis. Despite a normal
appetite, an animal suffering from JD develops can develop chronic diarrhoea or ill thrift, leading to
a gradual loss of bodyweight, emaciation and eventually death. All animals showing signs of
disease will inevitably die. There is no treatment. In Australia, BJD predominantly occurs in areas
of the southern states, and particularly in dairy cattle herds. It is less common in beef herds. There
is a cattle strain - bovine Johne’s disease (BJD) which affects all of the above species except
sheep, and a sheep strain - ovine Johne’s disease (OJD) which affects sheep.
How is it spread
The bacteria may be found in the faeces of infected animals. Young animals are most susceptible
to infection by ingestion of M paratuberculosis either when suckling their dam or grazing
contaminated pasture. The bacteria survive in faecal material and on pastures where other
animals can pick up the infection. In damp conditions, bacteria can survive in the environment for
up to a year.
The bacteria invade the lining of the small intestine and lymph nodes. The disease develops very
slowly and very few animals test positive to the disease until they are adults. Unfortunately, in the
meantime they can be shedding the bacteria in their faeces, possibly infecting other animals.
In infected animals not displaying symptoms of disease, the shedding of the bacteria may be
delayed and intermittent. Healthy carrier animals with no signs of disease can shed the bacteria
but it is also possible that infected animals may not be shedding bacteria at all times. This means
testing for the disease is very difficult.
How is it controlled
The National Johne's Disease Control Program (NJDCP) aims to help livestock industries to reduce
the spread and impact of Johne's disease in Australia.
Key components of the NJDCP are the Standard Definitions, Rules and Guidelines (SDR&Gs) for
different BJD zones and areas, movement controls between zones and areas and official disease
control programs.
The following link will provide more information on Johne’s Disease
http://www.animalhealthaustralia.com.au/programs/jd/jd_home.cfm
Northern Territory has a “Protected” status for BJD and is regarded by the rest of Australia as
having a very low prevalence of BJD, only being detected when infected animals are introduced
from interstate. To maintain this status Northern Territory has a policy of eradication of the disease
if it is suspected or shown to be present in a herd. BJD has been introduced into Northern Territory
herds following importation of infected animals from interstate on three occasions in 1976, 1994
and 2001 and was successfully eradicated from each herd with no further spread within the herd or
to other herds.
DEPARTMENT OF PRIMARY INDUSTRY AND FISHERIES
Diagnosis
Blood samples: Blood can be collected from live animals to test for Johne’s disease. Results
from a blood test are rapid but inappropriate for the assessment of individual animals as false
positives and negatives can occur. This test is less reliable than others for the true status of the
animal.
Faecal culture: Samples from the faeces are taken in an attempt to grow the bacteria the
laboratory. This test provides a reliable result however if the animal is not shedding bacteria at the
time the faeces is collected (due to early stage of disease or intermittent shedding) the result can
be inaccurate. A follow-up sample is needed for negative test results.
Tissue culture: Samples from a range of animal tissues, including the intestines and associated
lymph nodes, are taken in an attempt to grow the bacteria in a laboratory setting. This test is the
definitive test however can only be taken once the animal has been destroyed.
Culture tests take up to 14 weeks to complete.
Histological examination:
Samples of tissue collected at post mortem are examined
microscopically. This test is specific and sensitive. However, the test is only available after the
animal has been destroyed.
The definitive test for JD is tissue culture.
Where to from here
Your Regional Livestock Biosecurity Officer will work with you to formulate a management plan.
All activities must be consistent with the national BJD SDR&Gs and the Livestock Act. Your
property will remain with a suspect status for BJD until the status of all suspect animals has been
satisfactorily resolved. The definitive result is ordinarily by tissue culture.
Options for dealing with Suspect animals
1.
Destroy the animal and obtain samples for histological examination and tissue culture.
Results available within 12-14 weeks. This will require the animal to be slaughtered and
sampled on-property.
2.
Isolate the animal from the herd and hold the live animal segregated for 6 months until test
results are available. Blood and faeces are collected from the live animal for ELISA and
faecal culture tests. A second faecal sample is collected 12 weeks after the first sample if test
results are negative to provide evidence that the animal is not shedding bacteria in the
faeces.
3.
Retain the animal in the herd long term. Whilst the animal remains alive and its status
remains unresolved, the status of companion animals cannot be resolved. It also increases
the risk of potential spread of disease. This will mean the property will remain with a suspect
status for BJD until a definitive test result can be obtained.
Department of Primary Industry and Fisheries pays for the testing costs of these animals. There is
no compensation available for the destruction of these animals.
If the animal can’t be located on the property, a sample of the herd will need to be tested to provide
evidence that BJD has not been spread to other in-contact animals.
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Property
The status of the property can only be resolved when a valid risk assessment and investigation is
complete. This will include identifying:
 the infected and infective status of the introduced bulls through laboratory testing
 how long the animal has been on the property
 what contact the animal may have had with other animals on the property
 what class, type and age of other animals it may have had contact with.
 and possibly a herd testing program
Until this risk assessment can be completed satisfactorily, your property will remain with a suspect
status for BJD and movement restrictions will apply. The objective of movement restrictions is to
protect susceptible livestock, market access and NT livestock industry from the adverse impacts of
further spread of disease.
For more information
For more information on BJD, please contact NT BJD Co-ordinator
Sue Fitzpatrick
Email: susanne.fitzpatrick@nt.gov.au
Ph: 08 8999 2123 | Fax: 08 8999 2146
Mob: 0407 498 003
Postal: GPO Box 3000, Darwin NT 0801
Website: www.nt.gov.au/d/animalhealth
Disclaimer: While all care has been taken to ensure that information contained in this document is true and correct at the time of publication,
the Northern Territory of Australia gives no warranty or assurance, and makes no representation as to the accuracy of any information or advice
contained in this publication, or that it is suitable for your intended use. No serious, business or investment decisions should be made in
reliance on this information without obtaining independent and/or professional advice in relation to your particular situation.
www.nt.gov.au/d/animalhealth
© Northern Territory Government
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