This is the first outbreak of ciguatera poisoning in the Indian sub-continent.
There is the risk of additional outbreaks due to toxic algal blooms resulting from climate change, ocean acidification leading to coral reef deterioration and nutrient run-off in the ocean eco-system, according to biologists of the country.
The contaminant toxin is believed to be the result of the accumulation of marine algae and the toxins they produce in the tissue of the fish species, which ultimately passes through and contaminates the food chain.
Over 400 fish species, including barracuda, hogfish, horse-eye jack, king mackerel and several varieties of snapper and grouper, have been implicated with this illness.
With an annual occurrence of about 50,000 cases, such infection is relatively common in several parts of the world.
Toxic algae like dinoflagellates are first consumed by herbivore fishes which subsequently become the food of predatory reef fishes. The toxin then accumulates in the tissues of the reef fishes and affects people who eat these contaminated larger fishes.
This toxin is harmless to fish but dangerous to humans as cooking does not destroy it, according to experts.
The symptoms of contamination after eating the affected fish may show up in a couple of hours.
Initially, gastrointestinal symptoms like diarrhoea, nausea and vomiting tend to appear. Gradually, a feeling of weakness and hypertension may occur in addition to complaints of intense itching.
While some mild to severe neurological symptoms are common with ciguatera, it may also lead to dizziness, impaired coordination, blurred vision and, sometimes, the state of coma in severe cases.