In the Rapid Review series, I briefly review the key points of a clinical review paper. The topic this time: Ciguatera poisoning
The paper: Thompson CA, Jazuli F, Taggart LR, Boggild AK. Ciguatera fish poisoning after Caribbean travel. CMAJ Canadian Medical Association journal. 2016. PMID: 27160878
What is it?
Ciguatera poisoning is a foodborne illness caused by eating large reef fish such as grouper, snapper, barracuda, and eel. It is the result of ciguatoxins, odorless and tasteless chemicals produced by plankton and subsequently bioaccumulated in larger reef fish. Unfortunately, ciguatoxins are not destroyed by either cooking or freezing. The disease has nothing to do with the handling, storage, or preparation of the fish.
Where are these toxins found?
The plankton that produce ciguatoxins are predominantly found in the Caribbean, but they can also be found in the Southern Pacific and Indian Ocean.
How common is it?
It is relatively rare, with only 51 cases reported over a 5 year period. However, given the range of symptoms and lack of structured reporting system, it is likely significantly under reported. It is more common than other fish poisonings, such as scombroid.
What are the symptoms?
The pathognomonic symptom of ciguatera is temperature reversal: cold objects feels hot or vice versa. However, this only occurs in 50% of reported cases. Gastrointestinal symptoms, such as nausea, vomiting, diarrhea, and cramping are common. Neurologic symptoms might include paresthesias, ataxia, and headache. Patients might also report myalgias, arthralgias, fatigue, dizziness, or generalized pruritus. Less often, patients develop cardiovascular complications such as heart blocks and hypotension.
What is the timing of the disease?
There is usually a delay of about 6-24 hours between ingestion of the contaminated fish and symptom onset. Gastrointestinal and cardiovascular symptoms usually only last a few days, but the neurologic symptoms can last for weeks to months.
How is the diagnosis made?
This is a clinical diagnosis. Investigations, if any, are focused on ruling out other causes of the patient’s symptoms.
What is the treatment?
There is no specific treatment. Management is watchful waiting. There are some triggers that have been reported to make symptoms worse that patients should be advised to temporarily avoid: alcohol, caffeine, peanuts, seafood, and exercise.
Can it be prevented?
The toxin cannot be destroyed by any food preparation techniques. Symptoms are proportional to the amount of toxin ingested. Aside from completely avoiding ingestion of large reef fish, recommendations focus on limiting exposure: eating smaller portions of implicated fish, eating smaller fish (<2kg) (that will have lower concentrations of toxin than larger fish) and avoiding certain parts of the fish that have higher concentrations of the toxin, such as the head, skin, viscera, and roe.
The predominant symptoms vary depending on where the fish originated. In the Caribbean, GI symptoms predominate, whereas neurologic and cardiovascular symptoms are more common in the Pacific and Indian oceans.