An Outbreak of Paralytic Shellfish Poisoning in Tasmania

Abstract

Paralytic shellfish poisoning (PSP) is a rare illness caused by eating shellfish containing paralytic shellfish toxins (PST). Toxins are produced during harmful algal blooms, which occur most years on the east coast of Tasmania. Contaminated seafood looks and tastes normal and toxins are not destroyed by cooking or freezing. Commercial shellfish farms are monitored for harmful algae and shellfish toxins, but wild shellfish are not and pose a potential public health risk.

A case of PSP was documented in Tasmania in 2011, and we are aware of anecdotal reports of cases in the 1980s and 1990s. We are not aware of cases elsewhere in Australia but harmful algal blooms have been detected in Victoria, South Australia and New South Wales.

Routine monitoring of commercial shellfish in 2015 detected a large bloom of Alexandrium tamarense on the east coast of Tasmania, which can cause PSP. Between 2 and 12 October 2015, four cases of PSP were identified. All were adults who ate wild mussels from the east coast of Tasmania and had onset of numbness or tingling of the face and muscle weakness from 30 minutes to 12 hours later. Two cases were briefly hospitalised, both recovered.

Since the outbreak, permanent signage at locations where shellfish are frequently recreationally foraged has been erected. Additional alerts are released during high risk periods based on surveillance of commercial sites by the Tasmanian Shellfish Quality Assurance Program. Several states in Australia are at risk of cases of PSP. We recommend active surveillance and multi-jurisdictional collaboration to manage this risk.