The Centre for Health Protection (CHP) in Hong Kong is actively investigating two ciguatera toxin poisoning cases that have resulted in 5 people becoming ill after eating coral reef fish late last week.
According to a CHP press release Tuesday:
The first case involved three women and a man, aged between 20 and 56, who developed symptoms of ciguatera poisoning including abdominal pain, limb numbness and diarrhea 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 hospitalization. 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 ciguatera poisoning including diarrhea, 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 hospitalization. She is currently in stable condition.
Investigation revealed that the fish was purchased from a market in Tai Po on March 24.
In excess of 400 species of fish are implicated in ciguatera food poisoning. The illness is relatively common in several areas of the world.
This toxin is the result of the accumulation of marine algae and the toxins they produce passing up the food chain. These marine algae hang on to dead coral and seaweed. They are then eaten by herbivore fish which are subsequently eaten by predatory reef fish which concentrates the toxin in its tissue. People get this food borne toxin from eating these contaminated larger fish. The reef fishes are more likely to get contaminated during storms and other turbulence.
After eating the affected fish (the fish does not get sick from the toxin and actually tastes good) in as little as a couple of hours symptoms may appear. Gastrointestinal symptoms like diarrhea, nausea and vomiting tend to appear early. Then a feeling of weakness and hypertension may occur in addition to complaints of intense itching.
Some mild to severe neurological symptoms are common with ciguatera; dizziness, impaired coordination, blurred vision and even coma may be seen in severe cases.
An unusual characteristic that is common in ciguatera is temperature reversal. This may be seen from 2 to 5 days after eating the fish. Hot objects seem cold and cold objects can give a shock-like sensation. There have been serious injuries because a person was unable to recognize extremely hot sensations. Other odd symptoms are food may taste metallic and teeth may seem painful or loose.
The gastrointestinal symptoms usually resolve in a couple days; however neurological symptoms may last for months or years. Symptoms may come back after ingesting certain foods and drinks; alcohol, caffeine, nuts and fish.
There are no laboratory tests to diagnose this disease and it’s based on clinical symptoms and a history of eating an offending fish. Some studies have shown that IV mannitol is effective in providing relief and recovery if taken within the first 72 hours of intoxication. Other than that most treatment is for the various symptoms the person may have.
So how can you prevent getting this potentially serious toxin? Prevention can be difficult since the toxin in the fish cannot be killed by cooking and there is no offensive odor or appearance to the fish. So the only way to truly try to prevent this intoxication is to avoid eating large reef fish or getting your fish through a reputable supplier.
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