Attacking fish poisoning

Developments

Attacking fish poisoning with science

By Michael Field

IT is almost folklore now, the story of the man in the Marshall Islands who survived a near lethal dose of ciguatera fish poisoning through a remark ably timely medical discovery.

It was a couple of years back when he was bought into Majuro Hospital. They tried what they had but nothing worked and the man’s fate was seemed sealed.

Two doctors, Luis Jain and Neal Palafox, had one last throw of the dice and looked at manitol, a diuretic drug used to treat patients who’ve had head injuries to prevent swelling of the brain.

They gave it to him intravenously and within an hour the crisis was over.

Now a Hawaiian company, Oceanit Test Systems, Inc. (Oceanit), has come up with a pioneering kit,

“Cigua-Check”, that promises to take the risk out of eating fish.

Ciguatera poisoning is caused by a neurotoxin found in dinoflagellate algae called Gambierdiscus toxicus. It is related to the deadly “red tides” that occur around the world and kill millions of fish.

In warmer tropical waters the algae settles on seaweed near the shore.

Reef fish, in particular, eat the seaweed and taken in the toxic dinoflagel late.

Scientists disagree as to whether the cause of the increase is due to an increase in the overall number of people fishing or to the degradation of the ocean environment that has caused an increase in the number of

dinoflagellates. Ciguatera poisoning can

increase dramatically after cyclones have damaged reefs.

When larger fish eat the smaller toxic fish, the toxin becomes concentrated in the fat, muscles, and organs of the carnivorous fish.

The most dangerous parts of the fish are the head and viscera where the toxin tends to concentrate.

The risk to people increases as the toxin moves up the food chain into larger and larger fish. Symptoms typically show up four to eight hours after eating a toxic fish.

The symptoms include general weak ness, diarrhea, muscle pain, joint aches, numbness around the mouth, hands and feet, and sometimes a reversal of the sen sation of hot and cold.

Symptoms can persist for days or weeks, but in a few cases, up to 14 months.

Occasionally, as in the case of a fisher man on the Hawaiian island of Kauai, who died after eating an afflicted Marquesan sardine, ciguatera poisoning can be fatal within a few hours.

Cooking does not eliminate the toxin, but rather actually concentrates the toxin by cooking away water in the fish flesh.

It has been around for a long time and was reported as early as 1606 in Vanuatu while Captain James Cook described it in New Caledonia in 1774. He wrote of his sick crew whose symptoms coincide with those described today.

Viscera from the same fishes eaten by Cook’s crew were given to pigs, causing their death.

Fishermen know the dangers and often take the risk while others will avoid areas they believe may be ciguatera hot. But until now there has been no easy way to know for certain.

Palafox, who now practices medicine in Hawaii after nearly a decade in the Marshalls, believes the new test will make a big difference in the region.

“During my time in the Marshall Islands, I learned that it was usually the job

of the head fisherman of a village to say what fish were safe and what places to fish were safe,” Palafox says.

Cigua-Check puts science into the issue. It was developed by Doctor Yoshitsugi Hokama, a professor with the John A. Bums School of Medicine at the University of Hawaii.

In the test, a rice-grain-sized sample of fish flesh is placed in a vial of liquid methanol.

A test stick is placed into the vial then removed, air-dried and placed in a second vial of purple solution.

After the specified period, the test stick is removed and rinsed in tap water, and the results are read. If after the test, the test stick remains white, the fish is safe to eat.

However, if the stick turns purple, it means the fish is dangerous to eat.

In laboratory tests Hokama claims a high level of accuracy, around 95 percent.

Oceanit environmental scientist Bob Bourke told Pacific Islands Monthly that the problem developing the test revolved around a simple test trying to find very low concentrations of the toxin.

Ingesting just 32 nanograms of the toxin could make a sensitive person ill while others might need up to 235 nanograms.

The body, he added, did not develop immunity to the toxin and fishermen, even with a steady diet of fish, might find them selves in the sensitive category.

In testing the product, Bourke said, they had only one instance where a fish was declared safe to eat and where the person who later ate it got sick. In laboratory test ing later they found the fish contained another poison, not ciguatera.

Bourke said the kit was currently under going certification from the US Association of Official Analytical Chemists which was expected by the end of the year. Once received they will approach the World Health Organisation and aid organisations to see if the kit can be more easily offered around the world.

“The goal is to take a minute to use and a dollar per test,” he said.

Currently Cigua-Check costs US$2O

for five tests and takes 40 minutes to per form each test.

It is attracting the interest of sailboat owners who often have to risk eating fish a

long way from help.

Outside Hawaii the product is available on the Internet at http://www.cigua.com ■