What is ciguatera, a new food poisoning that has already arrived in the Canary Islands

Puerto de la Cruz (Tenerife)There was great expectation to know what scientist Ana Gago-Martínez would explain, a professor at the University of Vigo, a researcher in Analytical and Food Chemistry and director of the EU reference laboratory for marine biotoxins. This is because the increase in cases of ciguatera poisoning, contracted by eating certain fish, has led to a significant effort by administrations and the scientific community to manage a potential health problem that, until a few years ago, was not characteristic of Europe. In her presentation at the Encuentro de los Mares congress in Tenerife, Gago-Martínez asked that the public be informed, but without causing alarm. We will try to summarize the key points of a potential risk, in order to comply with the scientist's request.

What is ciguatera

Ciguatera is an food intoxication caused by natural toxins from the marine environment, ciguatoxins. These are generated by a type of microalgae (gambierdiscus and fukuyoa), which enter the food chain. These microalgae are eaten by an herbivorous fish, then a carnivorous fish eats the herbivorous one and then, this larger fish is caught, and that's how it reaches human consumption. These microalgae are not native to our coasts, but rather to the Caribbean and the Pacific. However, for some years now, they have begun to appear on European coasts such as Madeira and the Canary Islands. The reasons are the climate crisis, changes in ecosystems, and the mobility of tourists and the fishing industry. Knowing which strain has arrived has been key to understanding the extent of the disease, as the Pacific strain is more serious than the Caribbean one.

When it appeared

There have been poisonings of this profile since The Odyssey by Homer to the chronicles of Alexander the Great, who forbade his soldiers to consume some fish. The term ciguatera comes from the naturalist Antonio Parra. He coined it in 1787 in Cuba, referring to the consumption of cigua, a sea snail. It was the Japanese Takeshi Yasumoto who in 1977 managed to identify what generated it. Subsequently, in 1989, another Japanese, Michio Murata, discovered its chemical structure and named it Cambierdiscus toxicus. This toxin is not killed by cold (freezing the fish) or heat (cooking it).

In Spain, the alarm was first raised in 2004, when a family of five caught a

cirvia in the Canary Islands. All of them contracted the disease. This case could be scientifically verified because remains of the consumed fish were preserved. Although at that time there was no technology to guarantee the presence of ciguatera 100%, Gago-Martínez was able to send samples abroad where they confirmed the positive result and it was established that the outbreak was the Caribbean one, the least aggressive. Even Yasumoto himself highlighted its low toxicological load. It was the first reported case on the islands, but since then there have been several outbreaks with a total of 212 people who have contracted the disease. It is estimated that worldwide, between 10,000 and 50,000 cases occur each year, despite significant underdiagnosis. And more so, because as it has been expanding in recent years, it reaches new areas where health services do not identify it.

These are the specimens to be analyzed before putting them on sale: the Roe deer (gambierdiscus, in the Mediterranean, has never found any contaminated fish. However, one must be vigilant with imported fish and with fishing that does not undergo any health control, such as sport fishing. The fish sold at fish markets are safe. But it must be kept in mind that they have been identified in fish imported from India. In addition, a very ambiguous European legislation must be addressed.

Fish susceptible to ciguatera contamination

These are the specimens that must be analyzed before being put on sale: the Amberjack (seriola spp) from 10 kilos, the Grouper (epinephelus marginatus) from 8 kilos, the Bluefish (pomatomus saltatrix) from 2 kilos, the comb grouper (mycteroperca fusca) from 7 kilos, and the Wahoo (acanthocybium solandri) from 35 kilos. “These chemical structures are very complex, and being able to detect and quantify them is important because toxicology depends on how much there is,” explains Gago-Martínez. The method applied is high-resolution mass spectrometry (HRMS).

What symptoms does ciguatera produce

When the disease is contracted, the symptomatology is as follows: gastroenteritis (nausea, vomiting, and diarrhea), tingling, thermal inversion (fever), and weakness. And although less frequent, cardiovascular problems. The treatment is the same as one might have with a flu or intestinal flu. In case it is suspected that there is a possibility of having contracted it, the remains of the fish that could be contaminated must be preserved so that it can be analyzed.