Bovine Johne???s Disease (BJD)
BJD has been recognised as a herd health and herd production issue for beef and dairy cattle for some time. The disease is caused by the bacterium, Mycobacterium paratuberculosis. Diagnosis is difficult as animals can be infectious and shedding the bacteria in their faeces long before they can be detected by diagnostic tests and long before they show clinical signs of disease.
Control is reliant upon careful herd management, adherence to strict movement controls, commitment to reporting and testing programs. For South Australia the national distribution of BJD has a significant impact on control of the disease. South Australia is geographically positioned between the States, and Northern Territory where there is little disease in the beef population and with which we have significant trade. Equally important is the State’s location adjacent to the Victorian dairy herd, which has a significant disease problem and is a source of many replacement dairy cattle.
An abattoir survey of 4,640 beef cattle in 1996 indicated that the prevalence of Johne’s disease in South Australian beef cattle was very low as no infected cattle were detected.
Johne's disease is considered as one of the most important causes of production loss in cattle worldwide. Apart from losses from protracted diarrhoea and death, infected animals produce less milk, have depressed fertility and are more susceptible to concurrent infections. BJD is a notifiable disease and detection is highly dependent on individual cattle producers and veterinarians reporting and investigating suspicion of disease.
In 2003, under the auspices of Animal Health Australia, the cattle industries and governments agreed to a national approach to Johne’s disease in cattle in Australia.