National TSE Surveillance Program

Australia is free of bovine spongiform encephalopathy (BSE) and scrapie and has been designated a "negligible risk" status (the lowest risk) by the World Organisation for Animal Health (OIE).

The primary purpose of the NTSESP is to support trade by maintaining a surveillance system for TSEs that is consistent with the OIE Terrestrial Animal Health Code and assures all countries which import cattle and sheep commodities that Australia remains free of these diseases. It is important that Australia meets this requirement to assure continued access to export markets.  The OIE Code includes:

• Chapter 11.6 Bovine spongiform encephalopathy
• Chapter 14.9 Scrapie

The program is managed by Animal Health Australia and is planned and implemented through the National Advisory Committee comprising representatives from the relevant livestock industries, the Australian Government and state and territory animal health agencies.

The NTSESP is a targeted component of Australia's overall disease surveillance effort, which has the purpose of providing cost-effective information for assessing and managing risks associated with trade in animals and products, animal production efficiency and public health. The overall system comprises both general and targeted surveillance. General surveillance comprises a wide range of activities to maintain a continuous watch over the livestock disease profile so that unexpected changes can be recognised. Activities include pre- and post-slaughter inspection at meatworks, inspection of animals at sale yards and other points of aggregation, farm visits by private and government veterinarians and results from laboratory testing.

The NTSESP is complemented by general surveillance for neurological disease in all animal species with intensive follow-up investigations of cases involving unexplained neurological signs. Intensive follow-up has uncovered a number of rare neurological conditions where a TSE has been ruled out. These investigations have shown that some hereditary diseases, plant poisonings, infectious diseases and musculoskeletal conditions can result in signs that mimic those of TSEs. They are of particular relevance to Australia because of their rarity, geographical remoteness and/or unusual circumstances of their occurrence. Resolving the causes of these conditions gives additional confidence that Australia's comprehensive approach to surveillance is detecting rare neurological diseases and ruling out TSEs.

Bovine spongiform encephalopathy

Active surveillance for BSE commenced in 1990 and was modified in 1998 with the development of the NTSESP. 

The NTSESP sampling design for BSE is based on the recommendations in the OIE Terrestrial Animal Health Code, 2008 Edition.  Australia is a country assessed by the OIE as BSE Negligible Risk and therefore should implement OIE Type B surveillance. The application of OIE Type B surveillance is designed to allow the detection of at least one BSE case per 50,000 in the adult cattle population at a confidence level of 95%. Australia's target is to achieve a minimum of 150,000 surveillance points during a seven-year moving window. Australia also meets the OIE recommendations that clinically consistent cattle are investigated regardless of the number of points accumulated and that cattle from the fallen and casualty slaughter subpopulations are also tested.

The Program involves the detailed examination of clinically consistent cattle collected at points throughout the production chain as well as examining 300 brains from fallen or casualty stock each year to satisfy the OIE Code recommendations and to aid in maintaining accreditation for the BioRad TeSeE rapid test.

The use of histopathology as the screening test for clinically consistent cattle is followed up with confirmatory testing at AAHL using a range of methods where required.  These samples (the entire brain and other parts) are submitted to laboratories around Australia for TSE testing and differential diagnosis can be explored. Summary results are reported via the National Animal Health Information System and the Animal Health in Australia report.

Specimen and information flows in the program are summarised in Diagram 1 below.

Scrapie

The Chapter of the OIE's Terrestrial Animal Health Code on scrapie surveillance for animals displaying clinical signs consistent with scrapie remains under study. However, the NTSESP scrapie sampling design is consistent with meeting the OIE's recommendations and is based on detecting scrapie with 99% confidence if it comprised 1% of neurological cases. It is assumed that there are about 80 million sheep in Australia and that 50 million of these would be over 18 months of age.  Thus the reference population of interest comprises the 5000 expected neurological cases from this group. This results in a recommendation to examine a minimum of 438eligible neurological cases each year assuming perfect sensitivity and specificity of the diagnostic system.

It is further assumed that neurological cases in sheep are uniformly distributed throughout Australia. The sampling fraction is therefore the same for each State and is applied to each State's sheep population to reach the numbers specified in the table below. While scrapie can occur in both sheep and goats, the NTSESP only applies to sheep. Scrapie in goats would only be seen in Australia as a ‘spill-over infection' from sheep.

These samples (the entire brain and other parts) are submitted to laboratories around Australia for TSE testing and differential diagnosis can be explored. The use of histopathology as the screening test is followed up with confirmatory testing at AAHL using a range of methods where required. Summary results are reported via the National Animal Health Information System and the Animal Health in Australia report.

Diagram 1
BSE and scrapie specimen and information flows

Specimen and information flows in the program are summarised in the Diagram 1 below.

Further information

Technical details of the program can be found in the  National Guidelines for Field Operations 2009/10 (1,898 KB) and the Australia and New Zealand Standard Diagnostic Protocols for TSE (2,087 KB) .

NTSESP Training Guide:

This guide contains images and footage of procedures which some viewers may find distressing. Discretion is advised.

This NTSESP Training Guide contains information for veterinarians, animal health officers, and producers collecting submissions for the National Transmissible Spongiform Encephalopathy Surveillance Program.

Page Updated: 20 August 2009