What is it?

Abalone Viral Ganglioneuritis, or AVG, is a viral disease that affects the nervous system of abalone and results in curling of the foot, swelling of the mouth, weakness and death.

Currently, species known to be susceptible to AVG in Australia are the greenlip abalone (Haliotis laevigata), blacklip abalone (H. rubra) and hybrids of these two species

There is no evidence that AVG has any effect on human health.

Where and When Might it Occur?

AVG was first detected in Australia in 2005 in two Victorian abalone processors, and subsequently in wild Victorian abalone stocks. It was later confirmed in Tasmania in 2008 in both wild stocks and at seafood processing facilities. Tasmania has reported further outbreaks of AVG in 2010 and 2011.

A similar abalone virus has been reported in abalone in Chinese Taipei.

AVG can be transferred between abalone via water and infected abalone, including abalone mucus.

Diagnosis

Outbreaks of AVG in both farmed and wild abalone populations in Australia are associated with the rapid onset of high mortality rates (up to 90 per cent) in all age classes.

Similarly, in Chinese Taipei, during the epizootic in cultured abalone (the water temperature was 16–19°C), both adult and juvenile abalone suffered from the disease, with cumulative mortalities of 70–80 per cent.

It was reported that death of all of the abalone in a pond could occur within three days of the onset of clinical signs.

Abalone may also demonstrate one or more of the following signs: irregular peripheral concave elevation of the foot; swollen and protruding mouth parts; eversion of the radula; minimal movement of the pedal muscle; excessive mucus production; absence of the marked extension of the foot shown in the righting reflex when healthy abalone are turned onto their backs; reduced pedal adhesion to the substrate.

Control/Treatment

Currently no vaccine is available.

Research on AVG in Australia has resulted in the development of new diagnostic tools, which have helped improve understanding of the disease.

Virus particles can also attach to commercial or recreational divers’ gloves and wetsuits which can be moved from one location to another, thereby spreading the virus. Governments can implement closures and decontamination protocols to prevent the virus from spreading from known AVG locations through human activity.