CHP investigating suspected ciguatoxin poisoning cases

3 July 2010

The Centre for Health Protection (CHP) of the Department of Health today (July 3) is investigating two suspected ciguatoxin poisoning cases affecting four people who had consumed coral reef fish.

The first case involved a man and a woman aged 63 and 48. They developed symptoms of ciguatoxin poisoning including limbs and oral numbness, diarrhoea, palpitation and reversal of sensation of hotness and coldness about six to 16 hours after eating coral reef fish in a restaurant located in Eastern District on July 1.

They sought medical treatment at Tseung Kwan O Hospital. The man was admitted in stable condition.

In the second case, a man and a woman aged 34 and 35 developed limb numbness, nausea, diarrhoea, generalised weakness, peri-oral numbness and dizziness about four to six hours after consuming coral reef fish at home during dinner on June 30. They sought medical attention at Kwong Wah Hospital. The woman was admitted in stable condition.

Investigation revealed that the incriminated coral reef fish were purchased from a fish stall in a wet market in Mong Kok.

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, reversal of sensation of coldness and hotness 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 members of the public should observe the following measures:

* Eat less coral reef fish.
* Eat small amounts of coral reef fish at any one meal and avoid having a whole fish feast in which all the dishes come from the same big coral reef fish.
* Avoid eating the head, skin, intestines and roe of coral reef fish, which usually have a higher concentration of toxin.
* When eating coral reef fish, avoid consuming alcohol, peanuts or beans as they may aggravate ciguatoxin poisoning.
* Seek medical treatment immediately should symptoms of ciguatoxin fish poisoning appear.
* Coral reef fish should be purchased from reputable and licensed seafood shops. Do not buy it when the source is doubtful.