The Department of Health has advised consumers to be cautious when eating large coral reef fish as seven ciguatera poisoning cases affecting 30 people, aged six to 74, have been reported in the last two days.

They developed symptoms of ciguatoxin poisoning after eating fish like areolated coral grouper and leopard coral grouper. Fourteen are in hospital in stable condition.

The department advised people to be particularly cautious of eating coral reef fish weighing over two catties, as they may contain ciguatoxin.

Ciguatera poisoning can occur in tropical areas and is mainly associated with the consumption of big coral reef fish which have accumulated the toxin in their body.

Larger fish are more likely to carry higher amounts of the toxin, but the chance of it accumulating in smaller fish cannot be ruled out. Cooking cannot destroy the toxin.

Numerous symptoms possible

People affected may show symptoms of numbness of the mouth and limbs, vomiting, diarrhoea, cold and hot spells, and painful joints and muscles.

Most people affected will recover without long-term health effects, however, if excessive toxin is consumed the circulatory and nervous systems will be affected.

To prevent ciguatera fish poisoning:

* avoid consuming large coral reef fish - the bigger the fish, the higher the risk;

* avoid eating the internal organs, especially the liver and gonads;

* eat only a small quantity of coral reef fish at any one meal;

* do not consume coral reef fish with alcohol and nuts; and,

* seek medical care when symptoms appear.