27 Mar 2012
The Centre for Health Protection (CHP) of the Department of Health is today investigating two ciguatoxin poisoning cases affecting five people who have consumed coral reef fish.
The first case involved three women and a man, aged between 20 and 56, who developed symptoms of ciguatoxin poisoning including abdominal pain, limb numbness and diarrhoea about two to 10 hours after eating a fish during dinner at home on March 23 and 24.
One of them sought medical treatment at Pamela Youde Nethersole Eastern Hospital and required hospitalisation. All are now in stable condition.
Investigation revealed that the fish was purchased from a market in Ap Lei Chau on March 23.
The second case involved a woman aged 48. She developed symptoms of ciguatoxin poisoning including diarrhoea, numbness over face and limbs, reversal of sensation of coldness and hotness and headache three hours after eating a fish at home at midnight of March 26.
She sought medical consultation at United Christian Hospital but did not require hospitalisation. She is currently in stable condition.
Investigation revealed that the fish was purchased from a market in Tai Po on March 24.
A CHP spokesman said ciguatera fish poisoning is not uncommon in tropical areas. It is mainly associated with the consumption of big coral reef fish that have accumulated the toxin in the body, in particular in internal organs, through eating small fish that consumed toxic algae in coral reef seas.
A 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 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 in the joints and muscles.
The spokesman said that most people affected by ciguatoxin would recover without long-term health effects.
However, if excessive toxin is consumed, the circulatory and nervous systems can 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; and
* Coral reef fish should be purchased from reputable and licensed seafood shops. Do not buy the fish when the source is doubtful.