Johnes disease test validation in beef cattle - collection of resource material.

Summary

Bovine Johne’s disease (BJD) is a significant issue for the dairy industry in south eastern Australia and a sporadic problem in beef cattle. Internationally, BJD is considered to be a significant threat to the livestock sector. Several studies have confirmed direct economic loss, but a greater threat exists because of a perceived link with Crohn’s disease in humans, and therefore concern exists about ensuring future market access for livestock products.

Animal health authorities in many countries have introduced, or plan to introduce, control programs for BJD. These will depend on accurate diagnostic tests, which are still lacking. Consequently there are large research and development (R&D) programs on BJD in the EU/Europe, Japan, New Zealand and North America and smaller research programs in many other places. For market access insurance, Australia needs to be engaged with R&D at an international level.

BJD can be diagnosed by detection of the pathogen, but there is a major constraint from lengthy delays between submitting samples to a laboratory and the availability of results. Because of this, rapid faecal tests have been developed, however validation is lacking. This project was developed to obtain samples for validation of the new test and process them using the best available culture method in parallel with the new test. This project found that faeces can be tested quickly and accurately using direct PCR. This can provide results within a few days rather than the previous three months for culture which necessitated considerable forward planning for cattle sales.

Objectives

This project was developed to obtain samples for validation of the new PCR test and process them using the best available culture method in parallel with the new test.

Key findings

The project was able to successfully validate the PCR test, showing that faeces can be tested quickly and accurately providing results within a few days rather than three months. The test may also be suitable for testing pooled faecal samples for herd and environmental testing.

Benefits to industry

Bovine Johne’s disease is a threat to the industry internationally, causing direct economic loss, as well as having a perceived link with Crohn’s disease in humans, and risking market access. Despite this, tests take three months to culture; receiving a negative test prior to sale requires considerable forward planning and inconvenience to the producer. The PCR test can return results in a few days and costs no more than the previous culture tests. Furthermore, it has potential to be used for pooled faecal samples which would enable a cheap method of herd testing, either to detect infection or to show that it is not present in herds in the Market Assurance Program.