23 Mar 2009
The Centre for Health Protection (CHP) of the Department of Health today (March 23) is investigating two suspected ciguatoxin poisoning cases affecting three people who had consumed marine fish.
The first case involved a 40-year-old woman. She developed symptoms of ciguatoxin poisoning, including perioral numbness, diarrhoea and weakness about 7 hours after eating marine fish at home on the night of March 20. She was admitted to Yan Chai Hospital and is now discharged in stable condition.
In the second case, one woman and one man, aged 30 and 32 respectively, developed numbness in the extremities, diarrhoea, weakness and vomiting about 11-13 hours after consuming marine fish at home during dinner on March 19.
Both of them sought medical treatment from private doctor and did not require hospitalisation. They are now in stable condition.
Investigation revealed that the incriminated marine fish were purchased from fish stalls in markets in Tung Chung and Fanling respectively.
A CHP spokesman said ciguatera fish poisoning was not uncommon in tropical areas. It is mainly associated with the consumption of 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.