It’s the last hour of a busy shift and you are looking forward to handing over a good room to your colleague. A 28-year-old male patient with nausea and vomiting pops up on your board.
You glance at his bed across from your computer and see a well-appearing, young man comfortably sitting on a stretcher.
Looks like an easy reassure and discharge.
You walk over and the patient tells you that he has no past medical history. He reports traveling from the Caribbean yesterday and when returning home having one day of nausea and vomiting (three times) and loose stools. These symptoms resolved several hours ago when he arrived in the ED. And while waiting to be seen, he ate some crackers without a problem. He has no bilious or bloody vomit, fever/chills, abdominal pain, surgical history, or urinary symptoms.
That was easy enough. I’ll take this freebie.
Then he tells you he did just notice some new symptoms in the last couple of hours. He initially ignored them since they were mild and didn’t make much sense. They include mild “pins and needles” sensation in his bilateral lower extremities, metallic taste in his mouth, his teeth feeling loose, and that when he entered the ED the metal door handle felt warm to touch.
You wonder why you can’t just get one straightforward case today.
He has no other symptoms based on your extensive questioning and no other neurological symptoms.
He has an unremarkable exam: normal vital signs, normal dental exam with no appreciably loose teeth, normal abdominal and neurologic exam.
You cannot figure out what is causing these symptoms, so you decide to give the patient a liter of normal saline, ondansetron, and send a comprehensive metabolic panel, magnesium level, and a complete blood count. You sheepishly sign the patient out pending labs and reassessment.
On sign-out, your much smarter colleague asks the patient if they recently ate any fish (which they did), and asks you if you considered ciguatera poisoning (which you did not).
Ciguatera Fish Poisoning (1) – Foodborne illness caused by eating large reef fish Ciguatoxins Molecular structure of a ciguatoxin. Graphical representation of algae containing ciguatoxins growing on a reef. (2)
– E.g., grouper, snapper, barracuda, and eel
– Most frequently reported seafood-toxin illness in the world
– Odorless and tasteless
– Produced by algae (dinoflagellates called: Gambierdiscus) -> accumulate in larger reef fish
– Not destroyed by either cooking (heat stable) or freezing
– Not related to handling, storage, or preparation of the fish
– Bind to voltage-gated Na channels to cause toxicity
Geography (1) – Caribbean Distribution of endemic, recently emerged, and imported ciguatera fish poisoning (CFP) cases. (2)
– Also found in the Southern Pacific and Indian Ocean.
– Expanding areas of outbreaks (e.g., Gulf of Mexico, Mediterranean)
– Cases arise from imported fish
– Outbreak in Queens in 2010-2011 (3)
Clinical findings (1) Gastrointestinal symptoms (often first symptoms) Neurological Symptoms (can occur with gastrointestinal symptoms or after they resolve) – 50% of cases Paresthesias (i.e., numbness or tingling) in the hands and feet or oral region Neuropsychological symptoms (days to weeks later) General Cardiac (early in disease course)
– Nausea
– Vomiting
– Diarrhea
– Abdominal cramping
– Metallic taste
– Sensation of loose teeth
– Generalized pruritus (itching)
– Headache
– Dizziness
– Temperature reversal (cold allodynia) – some sources state it’s a pathognomonic symptom (but can also be seen in neurotoxic shellfish poisoning)
– Confusion
– Memory
– Difficulty concentrating
– Depression
– Irritability
– Fatigue
– Myalgias
– Arthralgias
– Heart block
– Bradycardia
– Hypotension
Time course (1) – 6-24 hour delay after ingestion before initial symptoms appear
– Gastrointestinal and cardiovascular symptoms: 1-4 days
– Neurological symptoms usually present in the first 2 days of illness, and can last for weeks to months
– Case reports of symptoms lasting for years
Diagnosis (1) – Clinical
– Often have sick contacts, history of eating fish in an endemic region
– Analytical testing of a remnant of the fish consumed is expensive and time-consuming, no rapid test
– FDA able to test fish
– Required reporting to CDC in NY
– Should report cases to poison control (can help with diagnosis and treatment)
Differential Diagnosis (1) Paralytic shellfish poisoning Pufferfish poisoning Neurotoxic Shellfish Poisoning Scombrotoxin Fish Poisoning Botulism Guillain–Barré Syndrome Acute Arsenic ingestion Organophosphate poisoning Gastroenteritis
– Contaminated (saxitoxins) bivalves
– Rapid onset neurological symptoms (paresthesias -> weakness, dysarthria, dysphagia
– More severe symptoms than ciguatera and different food exposure
– 25% mortality rate
– Tetrodotoxins (improperly prepared)
– Severe weakness/paralysis
– Contaminated (brevetoxins) shellfish
– Gastrointestinal and neurological symptoms
– Can also cause cold allodynia
– Exposure history helps differentiate from ciguatera poisoning
– Ingestion of fish with high histamine levels (improper processing or storage)
– Flushing, rash, hives, headache, dizziness, sweating, gastrointestinal symptoms
– Severe cases: respiratory distress -> bronchospasm and vasodilatory shock
– Food-contaminated botulinum toxin
– Gastrointestinal symptoms, severe weakness -> respiratory failure
– Likely autoimmune reaction
– paresthesia -> ascending motor weakness
– Gastrointestinal symptoms -> peripheral neuropathy
– Exposure (e.g., fertilizer)
– Nausea, vomiting, and abdominal discomfort similar to ciguatera poisoning
– Cholinergic symptoms: salivation, bronchorrhea, diaphoresis
– Either from contaminated food or an infected person
– Combination of nausea, vomiting, abdominal discomfort
– Certain cases can have neurological symptoms (E. coli, Shigella)
Treatment (1) Contact local poison control center Supportive Mannitol (4) One randomized control trial showed significant reduction of symptoms (4, 5) Another randomized double-blind control trial showed no difference from saline (6) Prognosis – Rarely fatal (can cause resp failure by resp muscle paralysis), convulsions, coma
– Correct electrolyte abnormalities
– Antiemetics
– IV fluids
– Intubation, vasopressors, atropine, pacing,
– Osmotic diuretic -> reduction of neuronal edema
– 1g/kg dosing
– Thought to reduce symptoms (especially neurological) and duration of illness
– 63 ciguatera poisoning with symptoms above a preset score
– Patients randomized to receive standard care (glucose, pyridoxine, ascorbic acid, and calcium gluconate) vs. mannitol
– At 24 hours patients receiving mannitol had a reduction in total symptoms (as judged by a predetermined score), paresthesias, and gastrointestinal symptoms
– Study results limited due to statistical analysis issues, use of a newly unvalidated scale, lack of blinding
– 50 patients on Cook Island with ciguatera poisoning and neurological symptoms
– Mannitol (25) vs. normal saline (25)
– No statistically difference in severity or resolution of symptoms at 24 hrs between the different groups
– Limited by small sample size, single site, and possible issues with maintaining blinding
– Excellent prognosis even if critically ill (with proper ICU level care)
– Symptom recurrence (weeks of months after)
– Triggers to avoid: alcohol, caffeine, peanuts, seafood, pork, chicken, and exercise.
Prevention (1, 7) – Symptoms are dose dependent, so smaller portions
– Avoid parts with higher concentration (head, skin, liver, intestines, roe)
– Avoid eating reef fish especially barracuda and moray eel – cannot tell if fish is contaminated
Informational poster from Florida’s Department of Health on Ciguatera fish poisoning. (8)
From the Archives:
Think outside the box- It can be exotically toxic! – the Perspective of a Newbie Doctor
References
nfranck
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