The Centre for Health Protection (CHP) of the Department of Health is today (June 21) investigating a suspected ciguatoxin poisoning case affecting four persons.
The case involves four females aged between 17 and 77 who developed symptoms of ciguatoxin poisoning including limb weakness, numbness and diarrhoea about four to 15 hours after consuming fish on June 19 (affecting three persons) and 20 (affecting one person) at home. Three of them sought medical attention and two were admitted to Princess Margaret Hospital and Pok Oi Hospital for treatment. They are in stable condition.
Initial enquiries revealed that the fish consumed was bought from a fish stall at Po On Road market in Cheung Sha Wan on June 19.
Ciguatera fish poisoning is not uncommon in tropical areas. It is mainly associated with the consumption of large coral reef fish which have accumulated the toxin in the body, particularly in internal organs, through eating small fish that consumed toxic algae in seas around coral reefs.
A larger fish is therefore more likely to carry a higher amount of the toxin. However, it is not easy to tell from the appearance of the fish whether it contains the toxin.
People affected may have symptoms of numbness of the mouth and limbs, vomiting, diarrhoea, alternating sensations of coldness and hotness, and pain in their joints and muscles.
"Most people affected by ciguatoxin will recover without long-term health effects, but if excessive toxins are consumed, the circulatory and nervous systems can be affected. The toxin cannot be destroyed by cooking," a spokesman for the CHP said.
To prevent ciguatera fish poisoning, the public should:
- Eat less coral reef fish;
- Eat small amounts of coral reef fish at any meal and avoid having a whole fish feast in which all dishes come from the same large coral reef fish;
- Avoid eating the head, skin, intestines and roe of coral reef fish, which usually have a higher concentration of toxins;
- 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 in doubt.
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