A 60 yo male presents to the emergency department with Ciguatera Toxicity. He is frightened by the symptoms he has developed. This morning he noticed some paraesthesia around the mouth. He also noticed that when he picked up a cold bottle of water it ‘burnt’ his hand. Also when he splashed cold water on his face or breathed in cold air-conditioned air, it felt like it was burning him. He also had significant pruritus over his chest..
His other most relevant history was that he had developed some nausea and vomiting the day before after eating some mackerel caught by a friend and frozen for three weeks. He had also eaten some of the same fish the evening before that with resultant nausea and vomiting.
What’s the diagnosis?
This is Ciguatera poisoning.
Ciguatoxin is produced by dinoflagellates and accumulates in reef fish(warm water fish). It is odourless, colourless, tasteless and is not destroyed by cooking.
The diagnosis is a clinical one. Symptoms begin within minutes or may be delayed for up to 24 hours. There are three organ symptoms most commonly affected:
GIT symptoms are usually simply nausea, vomiting and diarrhoea.
Neurological symptoms can include paraesthesias, either extremity or circumpolar. They may also include ataxias and the classic symptom ‘cold allodynia’, where cold feels hot.
Neurological symptoms may have a more delayed onset i.e. 48-72 hours and may last for a longer period of time.
Cardiovascular symptoms may include bradycardia and hypotension.
Other symptoms may include myalgias, severe pruritus and the feeling of teeth being loose. The patient may also experience pain on urination or defecation.
There are no real investigations to prove the presence of the toxin, certainly none, we would use at this point of time in the emergency department. There is a monoclonal antibody immunoassay(1), that can detect the poison, but this is not prime time.
This is mostly supportive.
Early intervention with activated charcoal may assist.
Neurological symptoms have in the past been treated with Mannitol(2), however recent studies have shown that it confers no benefit over normal saline(3). Amitriptyline is effective in treating the pain syndrome.
Cardiac symptoms such as hypotension, respond well to volume, but may require pressers and bradycardia respond to atropine.
Patients will need admission if there are cardiac and neurological symptoms. On discharge they need to keep away from alcohol and nuts and nut oils and reef fish following exposure, for up to 6 months, as these may re-ignite symptoms.
The patient was commenced on amitriptyline and paracetamol. 24 hours later, all symptoms had resolved, except for some mild allodynia. He was discharged home on amitriptyline, with advice to avoid fish and alcohol and to review with local doctor.
1 Tsumuraya T, Fujii I, Hirama M. Production of monoclonal antibodies for sandwich immunoassay detection of Pacific ciguatoxins. Toxicon. 2010 Oct. 56(5):797-803
2 Eastaugh JA. Delayed use of intravenous mannitol in ciguatera (fish poisoning). Ann Emerg Med. 1996 Jul. 28(1):105-6
3 Schnorf H, Taurarii M, Cundy T. Ciguatera fish poisoning: a double-blind randomized trial of mannitol therapy. Neurology. 2002 Mar 26. 58(6):873-80