Seafood poisoning at Vizhinjam restaurant: doctors suspect neurotoxin

The food safety authorities as well as doctors who treated persons who were hospitalised in an acute condition after consuming seafood from a restaurant at Vizhinjam have pointed to the possibility that the seafood, which triggered serious symptoms, being contaminated by a naturally occurring and extremely potent marine neurotoxin, possibly, tetrodotoxin (TTX).

They also pinpoint fish roe to be the possible culprit, as all those who ended up in hospitals had consumed this seafood delicacy. This also explains why others who had food at the same restaurant, also other members of same groups who ate seafood together, did not fall ill.

Three out of a six member family had been seriously ill after consuming seafood from a restaurant at Vizhinjam on the night of February 16 and two died within hours.

Following this, more reports of people taking ill, all of whom had eaten at the same restaurant on the same day, came out. In all, following the first incident, six more cases of acute illness had been reported, of whom two have been admitted to the Government Medical College hospital, Thiruvananthapuram, and one each to two private hospitals in the city.

Having ruled out primary evidence of food poisoning due to spoilage or bacterial contamination of food, food safety officials had veered towards the angle that fish contaminated by marine algal toxins could have led to the “food poisoning” episodes. They based their suspicion on the fact that Ciguatoxin had been recently detected in some samples of red snapper (Chempalli) fish sourced from the Tamil Nadu coast.

However, the short duration within which people became acutely ill, the predominantly neurological symptoms displayed by the affected and death within a few hours are clinically consistent with TTX poisoning, doctors believe.

Tetrodotoxin (TTX) is one of the most powerful neurotoxins known, which is very heat-stable, and is found coating the eggs of Puffer fish. This toxin has no known antidote and ingestion leads to severe, often fatal, paralysis. TTX was initially believed to be present exclusively in the puffer fish family (Tetraodontidae) but after 1964, TTX has been detected in several marine and terrestrial species too.

According to literature, TTX accumulates in the puffer fish through the food chain, starting with marine bacteria as a primary source. In marine pufferfish species, toxicity is generally high in the liver and ovary, which means that the fish roe would contain lethal amounts of the neurotoxin.

In the case of one patient recovering at one of the private hospitals, he was the only one among the group of friends who visited the Vizhinjam restaurant, who ate fish roe and he was the only one taken sick. “He had gone to bed soon after dinner and when he woke up five hours later, he experienced weakness of limbs and had trouble balancing himself or even sitting down. Electrophysiological studies showed rapidly progressing Gullain-Barre syndrome. He is improving now that he’s under treatment,” hospital sources said.

“We are terribly constrained by the fact that we have not been able to take samples of the cooked dish or the raw samples of the food these people consumed. But it does look like fish roe is the villain here. In the case of another family who had eaten at the restaurant, only two persons who consumed fish roe ended up ill,” food safety officials pointed out.

Food safety officials had learnt that the fish roe that was served in the restaurant on the night of February 16 had been sourced by the restaurant from Muttom in Tamil Nadu the previous day. “The fish roe was not from one particular species, it was a mixed bag, we were told. We had informed the Tamil Nadu food safety authorities on the need for conducting toxicology studies on the roe samples,” officials said.

The results of the chemical analysis of internal samples collected from the deceased is awaited, which alone would confirm the cause of death.