AUCKLAND: Pacific Island societies sometimes test freshly caught fish for deadly poison by feeding it first to the elderly, scientists have claimed.

Dr Lore Fleming of the University of Miami School of Medicine made the claim in a recent paper.

“Using a household pet or even elderly relative as a simple bioassay was and may still be practised in many island communities,” she said in her paper.

“Otherwise, only expensive ponderous bioassays in such animals as the mongoose, rat and cats were available for screening ciguatoxin-contaminated fish until 10 years ago.”

A laboratory test now exists for ciguatera poisoning, which afflicts at least 50,000 people a year worldwide, according to the United States Centers for Disease Control.

In an e-mail to AFP Fleming could not name a Pacific society using elders as guinea pigs.

“I (and I believe my colleagues) have heard anecdotal stories from our colleagues in the South Pacific concerning past use of pets and even elderly people as a sort of “bioassay” for the toxicity of fish but I cannot think of a documented reference,” she said.

But one of her references, Dr Richard Lewis of the University of Queensland, Australia, said he also knew of the approach.

“In some localities the head of the family will eat fish from a high-risk area to establish safety,” he said in an e-mail.

If old people are used as poison-testers in the Pacific, it is not widely known as AFP reporters throughout the region, including in high-risk areas such as Fiji and the Marshall Islands, have not come across it.

Deaths are very common, however; last year a family of six died in Kiribati after eating infected fish.

Globally few people die directly from ciguatera although scientists argue about the death rate. One expert puts it at around 0.1 per cent of all cases but there a radical variations.

Indian Ocean ciguatera is much more likely to be fatal while Pacific and Caribbean ciguatera have different effects on the body.

Ciguatera is a real threat in the Pacific, where most societies are dependent on marine life. It is caused by a neurotoxin found in algae related to the deadly “red tides” that kill millions of fish around the world.

In the Pacific ciguatera most commonly occurs in reef fish, and there is virtually no common way of testing for it. Cooking concentrates the toxin by removing water in the fish’s flesh.

Symptoms typically show up four to eight hours after eating a toxic fish. They include general weakness, diarrhoea, muscle pain, aching joints, numbness around the mouth, hands and feet, and sometimes a reversal of the sensation of hot and cold.—AFP