National priority: improving productivity and profitability of fishing and aquaculture.

The development of a guideline to investigate and understand disease outbreaks of unknown cause aligns with AQUAPLAN objectives for 2021- 2026 as per the draft document. The objectives were developed through extensive consultation with industry and government. This project was identified by the Aquatic Animal Health and Biosecurity Subprogram as a priority for the current call for applications.

Aquatic emergency animal disease outbreaks are a substantial threat to aquatic animal production and aquatic environments. The nature of aquatic emergency animal diseases makes them difficult to manage as they are often highly pathogenic and affect both wild and farmed populations. Further, new and emerging diseases are common, and eradication is typically challenging due to the presence of wild reservoir hosts.

Emerging diseases are challenging because reliable diagnostic methods are often not available and epidemiological information to guide responses may be absent. These circumstances present difficulties for decision making and disease investigation because there may be competing priorities between the need to learn about a disease and the need to contain or eradicate it. While the circumstances of each outbreak differ, general principles and approaches apply and if they are documented they can be used to guide responses to emerging diseases.

This project is focussed on developing a guideline to investigate and understand disease outbreaks of unknown cause. The ability to control an outbreak of a disease of unknown cause can occur independently of having knowledge of the aetiological agent. The basic epidemiologic tools used in classical outbreak investigation methodologies can provide insights into factors such spatial, temporal and animal elements of the outbreak. Such approaches are routinely used in terrestrial outbreaks of unknown aetioology and have been instrumental in aiding control, for example the Hendra virus outbreak in horses in the 1990s.

As aquaculture continues to expand at a rate approaching 6% per annum, new diseases will emerge and control strategies will benefit from this approach.