THINK ON THESE | Watch out: Don’t be a victim of paralytic shellfish poisoning

I love eating meat. But as I grew older, I started to change my way of eating. Now, I eat mostly seafood. Most of them are good for your health. But lately, however, there are some precautions before eating them.

One of those things that makes me worry before eating seafood is red tide.

Last September 8, the Bureau of Fisheries and Aquatic Resources (BFAR) issued Bulletin No. 21 stating that shellfishes collected from coastal waters of Altavas, Batan, and New Washington in Batay Bay, Aklan; Ivisana nd Sapian in Sapian Bay, Capiz; Gigantes Islands, Caries in Iloilo; Dauis and Tagbilaran City in Bohol; and Dumanguillas Bay in Zamboanga del Sur were found to be “positive for toxic red tide that is beyond the regulatory limit.”

All types of shellfish and alamang gathered from those coastal waters “are not safe for human consumption,” BFAR admonished. But fish, squids, shrimps and crabs are safe to eat “provided that they are fresh and washed thoroughly.” Internal organs of those such as gills and intestines should be removed first before cooking.

In Davao Region, the BFAR said the following coastal areas are free from toxic red tide: Balite and Pujada Bays in Mati City, Davao Oriental; Malalag Bay in Davao Occidental and Davao del Sur.

Contrary to common belief, red tides do not necessarily produce a red discoloration on the water – just like what happened during the time of Moses (although there were some notions that it was the first ever recorded red tide in history).

“It may also reflect sunlight as a pink, yellow, orange, violet, blue, green and brown discoloration,” wrote Cesar E. Tordesillas in an article published in Health News some years back. “But since red is the most common pigment, the phenomenon came to be known as red tide.”

Dr. Rafael D. Guerrero III, an academician with the National Academy of Science and Technology, says red tide is the discoloration of the sea caused by the sudden proliferation of plankton blooms. A main constituent of red tide is algae, a group of primitive plants dating to the first terrestrial life.

The microscopic killers in most cases are algae that occur in the form of dinoflagellates, tiny single-cell organisms that usually photosynthesize and contain chlorophyll but also have the animal-like trait of bearing twin tails, which whirl the organism forward.

According to Dr. Guerrero, dinoflagellates “can swim at the maximum rate of one meter per hour.” There are 2,000 types of dinoflagellates known to science, but only 20 species produce toxins or poisonous substances that kill human beings.

How red tide organisms appeared in the country is still unknown. Some scientists believe the red-tide causing organism may have been introduced here through the ballast water of ships coming from other Pacific countries where the causal organism is endemic.

Favorable conditions for red tide organisms include the right temperature and amount of nutrients. “During the day, the seeds are found near the surface where they receive sunlight for their photosynthesis activities,” said the Cavite-based International Institute of Rural Reconstruction (IIRR). “At night, they occur deeper in the water column where they receive nourishment.”

The organism multiplies asexually and rapidly during its productive stage, which results in bloom. During dormancy, the organism reproduces sexually and forms cysts that “hibernate” in the sediment until activated by favorable conditions.

Some marine scientists believe that red tide outbreaks are linked to pollution. Take the case of Manila Bay. Monitoring in 1994 by the Environmental Management Bureau of the Department of Environment and Natural Resources showed that some parts of the bay were “not fit for food production.” No wonder, the red tide keeps coming back in the bay.

Dinoflagellates serve as food to shellfish and other marine bivalves. When shellfish ingest too much of these, the shellfish become contaminated with red tide poison proven to be deadly to human beings. The most common shellfishes infested by red tide are mussels, oysters, scallops, cockles and limpets.

Dr. Guerrero says people get poisoned even if the contaminated shellfish is cooked because the toxin is not destroyed by heat. The poison in the red tide organism is known as saxitoxin. It is a water soluble salt that affects the nervous system. The potency of saxitoxin has been reported to increase by acidic chemicals like vinegar used in preparing common Filipino dishes such as adobo and paksiw, and the hydrochloric acid present in the human stomach.

In medical parlance, red tide poisoning is called paralytic shellfish poisoning (PSP). “Its symptoms appear 30 minutes after eating the contaminated shellfish, and are a numbness and tingling sensation around the lips, tongue, mouth, face and jaw. Headache, dizziness and nausea follow,” Bajarias informed. These symptoms may be mistaken for drunkenness and may be aggravated by alcohol consumption.

“In severe cases, it would later progress to paresthesia (muscular paralysis) of extremities with a feeling of lightness, numbness and/or periorbital edema (swelling around the eyes), difficulty of movement and breathing,” Bajarias further explains. “Finally, there would be respiratory failure that causes the eventual death of the victim. Death generally occurs within 17 hours after the onset of the symptoms.”

Doctors say the first thing to do in a poisoning case is to empty the victim’s stomach by giving the victim an oral emetic or simply by inserting a finger into the throat to induce vomiting. Since the toxin dissolves in water, the victim may also be given plenty of water to induce urination and minimize gastrointestinal absorption of the toxin.

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