Livestock biosecurity factsheet
Current at 12 June 2014
Check for updates at agric.wa.gov.au
Bovine Johne’s disease (BJD)
By Mia Carbon, Animal Disease Control Manager
What is bovine Johne’s disease?
The first sign in dairy cattle is often a drop in milk
production.
Bovine Johne’s disease (BJD) is an infectious
disease of cattle that can also affect other
ruminants such as goats, alpaca and deer. This
factsheet refers mostly to cattle but is also
applicable to other susceptible species.
The diarrhoea caused by BJD has a characteristic
watery green appearance and foul smell. The
appetite remains normal although infected cattle
may be more thirsty than usual. There is no fever.
BJD causes chronic wasting and incurable
diarrhoea leading to deaths in mature cattle. It
causes reduced production levels even before the
animal is noticeably unwell.
BJD is caused by the bacterium Mycobacterium
avium subsp. paratuberculosis (cattle strains),
commonly referred to as Mycobacterium
paratuberculosis. The bacteria multiply in the small
intestine of the animal, causing a thickening of the
gut lining that reduces the animal’s ability to
absorb food and water.
BJD has a long incubation period and infected
animals often do not show signs until they are
three to four years old. Because of its slow course,
animals showing obvious signs of the disease may
only occur sporadically within herds. If BJD is left
unmanaged in a herd, a high proportion of the
cattle may become infected after a long period.
Infected animals die a few weeks to several
months after the onset of signs.
Stressful events such as calving, producing milk,
and a lack of feed or poor feed may cause infected
cattle to start showing signs of BJD.
Producers should contact their private veterinarian
if their animals start showing signs of wasting and
diarrhoea or if there are any concerns with the
health of the herd. Industry-funded rebates are
available for BJD testing. These rebates aim to
encourage producers to test eligible animals with
signs of BJD so that Western Australia has enough
surveillance information to provide evidence of its
BJD status. Visit agric.wa.gov.au for rebate forms.
Owners of infected herds can manage the disease
by culling cattle showing signs of the disease, by
grazing management and, in dairy herds, through
hygienic calf-rearing practices.
Where does BJD occur?
BJD occurs in all cattle-raising countries of the
world, including Australia. BJD has been present in
south-eastern Australia for more than 70 years. It
is more prevalent where cattle are grazed at high
stocking rates in cool moist climates, and therefore
is most common in dairy herds. The disease is
present at much lower levels in beef herds.
Image 1 Intestines of BJD infected animal
showing inflammation and thickening
Signs of BJD
How does BJD spread?
The main feature of BJD in cattle is persistent
Infected cattle spread BJD when they excrete
scouring in mature animals that does not respond
bacteria in their faeces. Bacteria can survive in
to treatment and leads to a gradual loss of body
faeces, soil or water for up to 12 months in cool,
condition, weakness, and death. The coat often
moist conditions.
becomes rough.
Important disclaimer
The Chief Executive Officer of the Department of Agriculture and Food and the State of Western Australia
accept no liability whatsoever by reason of negligence or otherwise arising from use or release of this
information or any part of it.
BJD spreads slowly so it may be many years
before it is recognised as being present in a herd.
This is especially so in herds with good
management and hygiene.
As BJD takes years to show signs in infected
cattle, and bacteria are present in the faeces long
before these signs are seen, it can be spread by
infected cattle that are not showing signs. This
means the infection can be passed to other cattle
in a herd before any signs of disease are evident,
and that apparently healthy cattle introduced to a
herd can bring the disease with them.
How is BJD detected?
Testing for BJD in live cattle is by means of a
blood test or finding the bacteria in faeces by
culture or detection of bacterial DNA. Finding
disease in euthanased or dead animals involves
looking at sections of gut under the microscope,
and growing the bacteria from faeces and gut
tissues.
Growing the bacteria in faeces or tissues (culture)
is the most sensitive method of detecting BJD in
infected animals and is considered the definitive
test. A sample of faeces from five animals may be
pooled to reduce the cost of the faecal tests.
Finding the bacteria in the faeces, however, relies
on cattle shedding the bacteria at the time of
testing. A proportion of infected cattle, particularly
young cattle or those in the early stages of
infection, will not be shedding bacteria in the
faeces. Shedding can also be intermittent.
For this reason, the sensitivities of BJD tests are
low when carried out on individual animals. It is
necessary to test a large representative sample of
cattle in a herd to get an accurate idea of the
herd’s disease status. The higher the numbers of
cattle tested, the higher the level of confidence in a
negative result.
What is the economic impact of BJD?
Figure 1 BJD stages of infection
Adapted from RJ Whittington &
ESG Sergeant, “Progress towards understanding
the spread, detection and control of
Mycobacterium avium subsp paratuberculosis in
animal populations.”
AVJ Vol 79, No. 4, April 2001 pp 267–278.
Which animals are most at risk?
Calves are the most likely to become infected by
BJD. Calves are most susceptible up to 30 days
old and remain at risk of infection until around 12
months old. Cattle over 12 months old are
relatively resistant to infection and, if they do
become infected, are very unlikely to develop
signs of disease or shed significant numbers of
bacteria in their faeces.
Calves most commonly become infected by
suckling on udders contaminated with infected
faeces. Cattle can also become infected by eating
pasture or drinking water contaminated by the
faeces of an infected animal, or from the milk of an
infected dam.
In dairy herds, BJD causes economic losses
through reduced milk production, reduced
conception rates and restrictions on trading.
The economic impact on beef herds, while still
present, is typically less significant – particularly in
a well-managed herd.
The level of infection in a herd increases over time
and if the disease is left unmanaged, the economic
effect of BJD becomes increasingly significant.
In 1996, it was estimated that BJD cost the
Victorian beef and dairy industries about $6 million
per year in production losses.
Over the past few years, some of Australia’s
competitors have instigated control programs for
BJD. A number of our export markets place BJD
conditions or restrictions on cattle and cattle
products.
How is BJD treated?
There is no treatment for BJD.
How is BJD managed in Australia?
In cattle with visible disease, calves may also be
infected in-utero.
BJD is a difficult disease to detect and control.
This is because of the long period of time between
infection and the appearance of clinical signs, the
Important disclaimer
The Chief Executive Officer of the Department of Agriculture and Food and the State of Western Australia
accept no liability whatsoever by reason of negligence or otherwise arising from use or release of this
information or any part of it.
difficulties in stopping the spread of disease from
infected dams to their calves, and the limitations of
the tests available.
The disease in Australia is managed via the
National Johne’s Disease Control Program, which
is coordinated by Animal Health Australia on
behalf of industry, supported by state and territory
legislation. Under the national program, zoning is
applied to areas depending on their level of
disease and disease assurances. This zoning
affects how the disease must be managed within
the zones, and the conditions for moving animals
both within and between zones.
Control Program, and vary depending on what
zone or area the cattle are from.
These conditions are designed to minimise the risk
of introducing disease in animals, and are given in
Form LB 1 Health Certificate for Movement of
Stock to Western Australia. The assurances in this
document, however, rely on current understanding
of herd disease status and so do not guarantee
disease freedom.
For more information, contact your local DAFWA
Biosecurity Officer or visit agric.wa.gov.au
How can I keep my property free of BJD?
Methods for determining disease levels in the
zones or areas include checking higher risk herds
and investigating any positive test results. As part
of this process, trace herds are investigated
according to the National Johne’s Disease
Standard Definitions, Rules and Guidelines.
More information on the National Johne’s Disease
Control Program can be found at
animalhealthaustralia.com.au
Has BJD occurred in WA?
In WA, prior to 2013, there have been nine cases
of BJD in cattle and one in an alpaca. These cases
occurred between 1952 and 2006. In each of these
cases, infection was proven or most likely to have
been introduced with infected animals imported
from outside WA. Each was eradicated by
destocking the infected herds. In the 2006 case,
tracing identified that infected cattle had been
moved to two other herds in WA. At-risk animals in
these herds were also destocked.
BJD bacteria have also been isolated from one
sheep, even though the disease is rare in this
species, and no disease was seen or found by
testing other sheep or cattle on the property.
In 1999, WA was recognised nationally as a BJD
Free Zone. This meant that, at the time, there was
no known disease and that an active surveillance
program had not found any disease.
The national standards allow for cases of BJD to
be found in a Free Zone so long as the disease is
eradicated and surveillance is carried out to
demonstrate the disease is no longer present.
What are the conditions placed on cattle
entering WA?
The conditions for moving BJD-susceptible stock
into WA are determined by the movement
conditions outlined in the National Johne’s Disease
Property owners or managers should consider
introducing embryos or semen rather than live
animals as the risk of introducing BJD with
embryos or semen is negligible.
If introducing stock, ensure they are from herds
that are free of the disease. This means an animal
health declaration should be obtained from the
person in charge of stock before the animals are
introduced onto a new property. In particular, if the
potential consequences of introducing animals
from a property with BJD are significant to your
business, you should seek assurances regarding
the disease status of any potential introductions:
Where possible, buy from properties in the Johne’s
Disease Market Assurance Program (CattleMAP),
or
Ask for a negative herd BJD ‘Check Test’ before
purchasing any cattle. The Check Test is defined
in the Standard Definitions, Rules and Guidelines.
If there are any concerns over the health of the
animals, producers should contact their private
veterinarian.
Maintaining secure boundary fencing, preventing
access to drainage channels and waterways, using
troughs for watering cattle, and insisting that all
visitors clean their boots, vehicles and equipment
before entering the property will assist in
preventing the introduction and spread of many
pests and diseases.
Where can I get more information?
More information about the National Johne’s
Disease Control Program can be found at
animalhealthaustralia.com.au
For more information about BJD and WA, visit
agric.wa.gov.au or contact:
Dr Tom De Ridder, BJD Activity Manager
Phone: +61 (0)8 9194 1420
Email: thomas.deridder@agric.wa.gov.au
Important disclaimer
The Chief Executive Officer of the Department of Agriculture and Food and the State of Western Australia
accept no liability whatsoever by reason of negligence or otherwise arising from use or release of this
information or any part of it.