Background
Why is BJD a problem?
What is the history of BJD in Australia?
Development of a national BJD program
Balla Balla Red Poll Stud has Cattle
MAP MN1 Status for Johne’s Disease.
Johne's disease is a serious wasting disease that
affects a wide range of animals. In Australia it has
been found in cattle, sheep, goats, deer, alpaca and
llama. Infection with the organism that causes Johne's
disease has been confirmed in a small number of kangaroos
and wallabies. The significance of this finding is
still being investigated.
It is caused by bacteria (Mycobacterium paratuberculosis)
that live mainly in animal intestines but can also
survive in the outside environment for several months.
While cross-infection between species can occur, different
strains of the bacteria cause infection in different
animals. The strain of bacteria mainly affecting cattle,
goats, camelids and deer in Australia is known as
bovine Johne's disease (BJD). The sheep strain of
the bacteria is called ovine Johne's disease (OJD).
It has also infected goats in Australia.
Johne's disease affects animals by causing a thickening
of the intestinal wall which blocks the normal absorption
of food. The animal is hungry and eats but cannot
absorb any nutrients. This results in wasting and
finally death. Diarrhoea and bottle jaw are also common
signs in cattle.
Australia is in the fortunate position of having relatively
little Johne's disease compared to most developed
agricultural countries. Large areas of the continent
are disease-free and a high proportion of its livestock
populations have no known infection. Australia is
at the forefront of Johne's disease control internationally;
a position widely acknowledged at the 7th International
Colloquium on Paratuberculosis held in Bilbao, Spain
11-14 June 2002.
Australians are actively involved in international
organisations dealing with Johne's disease, such as
the World Organisation for Animal Health (OIE).
BJD is a debilitating disease that can
have severe economic effects if it is left uncontrolled
and allowed to build up in herds or areas. Infected
animals often do not show signs until late in life
and can be spreading the bacteria in their faeces.
Most of Australia has little or no BJD and requires
cattle from BJD-free regions or low-risk regions and
herds.
BJD was first recorded in Australian
cattle over 70 years ago. It now occurs in the states
of Victoria, New South Wales, Tasmania and South Australia.
Approximately 1350 cattle herds are known to be infected
in south-east Australia.
It is most common in dairy herds, however
the disease also occurs in beef cattle, goats and
alpacas. The first case was detected in deer in 1999.
Australia is in the fortunate position
of having relatively little BJD compared with most
developed agricultural countries. To prevent BJD from
spreading further, zoning for BJD was introduced in
1999. Zoning involves placing different regions of
a country into a certain 'zone' according to the region's
level of disease risk and control. Restrictions are
then placed on the movement of animals between zones
and animals have to meet certain standards for movement.
Western Australia was declared a BJD
Free Zone in August 1999. Queensland and the Northern
Territory have traditionally also been free of the
disease and were declared Protected Zones, along with
a large part of New South Wales. Protected status
has been extended to most of NSW and northern pastoral
areas of South Australia. Southern South Australia,
Victoria and parts of NSW are Control Zones. The main
island of Tasmania is currently a Residual Zone, but
Flinders Island and the rest of the Furneaux group
are a Protected Zone.
Higher status zones protect their favourable
status by placing controls on animals moving from
lower status zones and by dealing with incursions
or existing infection. The minimum standard now requires
some level of herd assessment, rather than a declaration
and a test of the individual animals to be moved.
That minimum standard for moving replacement cattle
from a Control to Protected Zone, or from a Residual
to Control Zone, is now an annual Check Test of 50
adult cattle.
In 1998, Animal Health Australia commissioned
a discussion paper on the future of Johne's disease
control in the Australian cattle industries. There
was general agreement that a detailed evaluation of
current programs was necessary in the first instance.
Funded by the cattle industries, the
evaluation looked at ten priority areas, including
surveillance methods for BJD in cattle, the effectiveness
of the CattleMAP and testing methods for BJD in cattle.
The former National Bovine Johne's Disease
Advisory Committee (comprising members from the Cattle
Council of Australia, the Australian Lot Feeders'
Association, the Australian Dairy Farmers' Federation
and governments) circulated the outcomes of the Evaluation
to stakeholders in May 2001 to determine recommendations
for future strategies to address bovine Johne's disease
in Australia.
A national meeting was held in September
2001 to progress the development of a national BJD
approach. Since then a draft national plan has been
developed by the cattle industries and governments
which was widely circulated for comment and in June
2003 a meeting was held with the industries and governments
where the "National Approach to Bovine Johne's
Disease in Australia" was endorsed as a means
to facilitate consistent and complementary programs
across the affected livestock industries and jurisdictions
For more information see www.animalhealthaustralia.com.au
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