Press Release

Ciguatoxin poisoning cases under investigation

25 October, 2004

The Centre for Health Protection (CHP) of the Department of Health today (October 25) reminded members of the public to be extra cautious when consuming large coral reef fish as they could contain ciguatoxin which may cause food poisoning.

The advice followed two reports of food poisoning cases suspected to have been caused by fish containing ciguatoxin.

The first case involved five men and seven women, aged from 28 to 57, who developed symptoms of ciguatoxin poisoning, such as limbs numbness, diarhoea and abdominal pain, after eating hump head wrasse in a Sai Kung sea food restaurant on October 22.

Their symptoms were generally mild and five of them sought medical attention from a private hospital in Kowloon and another one consulted a private doctor. They are all in stable condition and none of them required hospitalization.

The second case was an imported case in which a 33-year-old woman and four of her Mainland relatives developed symptoms of ciguatoxin poisoning after eating moray eel in Dongguan on October 21.

They were admitted to a local hospital. The woman returned to Hong Kong on October 24 and was admitted to Prince of Wales Hospital. She was discharged today.

A CHP spokesman said ciguatera fish poisoning was not uncommon in tropical areas. It is mainly associated with the consumption of a big coral reef fish which has accumulated the toxin in its body, in particular internal organs, through eating small fish that consumes toxic algae in coral reef seas.

The larger fish is therefore more likely to carry higher amounts of the toxin. However it is not easy to tell from the appearance of the fish if it contains the toxin.

People affected may show symptoms of numbness of the mouth and the limbs, vomiting, diarrhoea and pain of the joints and muscles.

The spokesman said that most people affected by ciguatoxin would recover without long term health effects. However, if excessive toxin was consumed, the circulatory and nervous systems would be affected.

"The toxin cannot be destroyed by cooking", the spokesman said.

To prevent ciguatera fish poisoning, the spokesman advised that the following should be observed:

• Coral reef fish should be purchased from reputable and licensed seafood shops. Do not buy it when the source is doubtful;
• Eating less coral reef fish, especially fish weighing over three catties;
• Eating small amount of coral reef fish at any one meal and avoiding to have a "whole fish feast" in which all the dishes come from the same big coral reef fish;
• Avoid eating the head, skin, viscera and roe of coral reef fish which usually have higher concentration of toxin;
• When eating coral reef fish, avoid consuming alcohol, peanuts or beans as they may aggravate ciguatoxin poisoning; and
• Seeking medical treatment immediately should symptoms of ciguatoxin fish poisoning appear.