6.05 - Diagnostic tools to assess infectious disease status

The diagnosis of the diseases listed in Table 1 is likely to require advice and assistance from your veterinarian. 

Table 1: Diagnostic tools to assess the bovine Johne’s disease (BJD) and mucosal disease (bovine pestivirus) status of introduced cattle

Disease Diagnostic

Bovine Johne’s disease (BJD)

  • An enzyme-linked immunosorbent assay (ELISA) serological (blood) test takes about three days and has a sensitivity of about 25–50% and about 1% false positives. It is suited to herd screening rather than individual testing.
  • Faecal culture tests to detect bacteria is more accurate than ELISA tests (sensitivity 30–50% and 0% false negatives) and take 2-5 months depending on the culture method used.  
  • Post mortem examination followed by histopathology and culture of gut tissues may be undertaken on serological positive animals.
  • No diagnostic tests are available for individual animals, or on a mob basis, that give a high level of assurance of freedom from BJD.

Mucosal disease (bovine pestivirus or bovine viral diarrhoea virus (BVDV))

  • There is a wide range of clinical signs depending on the strain of virus and time of infection. Signs can vary from mild diarrhoea to chronic ill-thrift and wastage in cattle up to 18 months to sudden death of cattle between six months and two years of age, and poor reproductive performance in breeding herd.
  • Serological testing for presence of antibody and testing of serologically negative cattle for presence of virus (antigen) is available. In addition, ear notch or hairs samples can be used.
  • The diagnosis of mucosal disease will require veterinary input to assist in diagnosis with autopsy, serological testing and histopathology.