The first documented case of neurotoxicity in two patients following octopus flesh ingestion in the Mediterranean : a case study from the Maltese Islands ( central Mediterranean )

Tetrodotoxin is a naturally occurring potent neurotoxin, widely distributed in marine animals, including a number of members of the Tetraodontidae fish family (e.g. Lagocephalus sceleratus, the silver-cheeked toadfish), a marine invasive species native of the Indo-Pacific region which is increasingly being reported from the Mediterranean. Various human fatalities have been documented globally as a result of intoxication through tetrodotoxin, but these have rarely been associated with the ingestion of octopus flesh. We hereby report the case of two patients from the Maltese Islands (central Mediterranean) who presented symptoms consistent with neurotoxicity, following the consumption of the well-cooked flesh of the common octopus. Both patients required supportive care, until complete recovery within a few days, with one of whom requiring intensive care. The reported cases of neuromuscular disturbances following the consumption of octopus flesh is highly suggestive of neurotoxicity due to tetrodotoxin poisoning, the first such cases documented for the Mediterranean waters, although alternative scenarios are also postulated in this study due to the lack of definite evidence for the TTX poisoning, including the release of histamine by psychrotrophic bacteria or the accumulation of HAB-related toxins. The postulated TTX intoxication mechanism involves predation by Octopus vulgaris, the common octopus or ‘scuttle’, on a toxic marine species harbouring tetrodotoxin.