New Toxic Algae Risk To Humans

A new species of toxic microalgae, which produces ciguatoxins, has been discovered by researchers at Spanish Institute of Oceanography (IEO) in the Canary Islands. This is the first one that has been described in Spain and is probably responsible for the cases of ciguatera that have been recorded in Canary Islands.

Santiago Fraga and Francisco Rodriguez, researchers at the Oceanographic Centre of Vigo of the Spanish Institute of Oceanography (IEO), in collaboration with scientists from other Spanish institutions (IRTA, CSIC and Universidad Autnoma de Madrid), have published in the journal Harmful Algae the description of a new species of toxic microalgae, a microscopic dinoflagellate which lives epiphytic on rocky coastal macroalgae.

The species, named Gambierdiscus excentricus and discovered in the Canary Islands, is the first described in Spain capable of producing ciguatoxin-like and maitotoxin-like toxins, the substances responsible for ciguatera, a food borne illness caused by eating certain fishes carrying the toxin.

This disease mainly affects tropical Pacific, the Caribbean and Indian Oceans, but cases have been recorded in the Canary Islands which is probably because of this new species.

The disease

Ciguatera is contracted by eating a fish that have accumulated the microalgae. The toxin is transmitted through the food chain and the largest carnivorous fish have the highest concentrations.

The toxin does not affect the fish, so it is not possible to visually determine which fishes may be poisonous and it can only be determined analytically. In addition, ciguatoxins are stable both cooking and freezing and do not smell or taste.

Most symptoms are common to different disorders: abdominal pain, diarrhea, vomiting, fatigue... But there may be two very distinctive and unmistakable: one is the reversal of temperature sensation, feeling cold by touching hot objects and hot to touch cold objects, and the other is a tingling in the lips and tongue.