RED TIDE - MAREA ROJA

The species responsible for red tides on the gulf coast of Florida is a dinoflagellate called Karenia brevis (formerly denominated as Gymnodinium breve.) It produces brevetoxins which produce respiratory irritation in humans.

Red Tide is commonplace during the warmer months and warm waters - thus Folklore warns us not to eat shellfish in months with no "r" in their names!

As in the case of poisonous fungi, scientific knowledge of poisonous algae is incomplete. Indeed, new and alarming toxic algae are still coming to light. In some parts of the world (Nova Scotia) three different algae are known to cause three, distinct, severe to deadly poisonings: 

The type of poison in Red Tide is Domoic Acid, an amino acid-based toxin which is potentially lethal.

SYMPTOMS

Shellfish poisoning, of whatever sort, is always unpleasant and often lethal. The onset of symptoms occurs as soon as the victim's digestive system starts to work on the infected shellfish. 

What is Red Tide? 

It is a toxic illness that is also called Paralyzed Intoxication by seafood that takes place when ingesting seafood that has eaten marine plankton which produces paralyzing poison. It is not any virus, bacteria or fungus, it is not an infection. Neither does it happen as a consequence of the exhibition of the shellfish in the sun.

What mollusks transmit it? 

The shellfish transmit it, such as the mussels, the clams, the cockles, the oysters, the vieyras and the cholgas. So do the sea snails. The other mollusks, as the octopi and the squids and other products of the sea like lobsters, prawns, shrimps crabs, fish, etc., don't present risk of transmitting this illness.

Does this happen frequently? 

No. There are certain times of the year when the quantity of plankton with paralyzing toxin increases abruptly. These periods vary so it is necessary to be informed in each case about the presence or not of the red tide in the area.

Is it a new disease? 

No, it has been known for centuries. Propagation has been favored in places that remained isolated of this illness during a long of time when the marine traffic increased. Argentina and Uruguay have been the last countries of South America affected by it.

Is there any external sign in the sea or the mollusks? 

No. The name of "red tide" has nothing to do with the color of the sea or with the presence of stains of that color in the water. The sea or certain parts of the coast can turn reddish without the presence of "red tide" and, conversely, "red tide" can be present without alteration of the color of the water.

As for the mollusks, these don't lose temper in their color, flavor, scent, or aspect, they don't get sick neither die, and there is no visible sign that allows you to identify which ones are infected and which ones are not. Only a specific test can detect the presence of the toxin.

Do you eliminate this toxin by cooking them? 

No. The heat doesn't eliminate the toxin, neither does the lemon, vinegar nor alcohol. These last substances, on the contrary, favor the absorption of the toxin.

It is important to keep in mind that the intoxication only takes place by ingesting the mollusks and not by touching them or manipulating them in any way, even when they contain a high toxin degree. Neither is it dangerous to drink sea water accidentally.

What is this disease all about? 

The intoxication is manifested at first by a tingling sensation in the lips, tongue, mouth and face. Then it extends and the muscular strength fails. Paralysis, breathing difficulty, nauseas, sickness and vomits can appear. These symptoms usually appear within the 30 to 60 minutes after the intake.

If the mollusks concentrate a high quantity of toxin, the intoxication can be mortal, and developed in very little time. Cases of death have been notified after fifteen minutes of the intake.

What is the treatment? 

There is no antidote. People have to be assisted as fast as possible in appropriate centers where the breathing function can be kept working until the toxin is metabolized completely, which happens around 12 hours after the eating. After this, the recovery is spontaneous. For all this, it is fundamental to look for a hospital as soon as you feel the first tingling sensation symptoms in mouth, face or fingers. If possible it is also important to take leftovers of the food ingested for their analysis.

How do you prevent it? 

The only form of prevention is to avoid ingesting mollusks in presence of red tide. In case of any doubt, acquire them in a store or in a restaurant because that merchandise has been previously controlled in official laboratories.