Ciguatera Fish Poisoning

Individuals with ciguatera fish poisoning typically experience gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea, abdominal cramping, and pain) within minutes to hours after eating contaminated fish, followed by neurologic symptoms of weakness, headaches, vertigo, perioral or limb paresthesias, muscle aches (i.e., myalgias), and joint pain (i.e., arthralgias). Cold allodynia, an altered sensation to temperature in which cold substances are perceived as hot, is a unique characteristic symptom of ciguatera fish poisoning but is not always present. In the early stages of toxicity, individuals may also experience bradycardia, hypotension, or shock. In some cases, individuals may experience neuropsychiatric symptoms (e.g., hallucinations, memory lapses, giddiness, depression). In rare cases, respiratory failure, coma, or death may result.  

Signs and symptoms can last for weeks to years. Recurrence of symptoms may continue to occur for years, especially in response to physical exertion or ingestion of caffeine, alcohol, nuts, chicken, pork, or eating any type of fish. 

Ciguatera fish poisoning is a clinical diagnosis based on symptomatology following reef fish consumption and the exclusion of other causes (e.g., pufferfish toxicity, organophosphate poisoning, multiple sclerosis). Currently, there is no readily available test to detect or diagnose ciguatera toxicity. While there are no human tests available, a sample of the consumed fish may be sent for laboratory testing to confirm the presence of ciguatera using in-vitro assays and liquid chromatography-mass spectrometry. However, the results of these tests are not readily available and are not useful for prompt diagnosis.  

There is no known antidote for ciguatera fish poisoning and therefore the mainstay of treatment consists of supportive care measures. Activated charcoal may be administered within the first few hours of ingestion to prevent further absorption if nausea and vomiting are not severe. In individuals experiencing dehydration due to severe vomiting or diarrhea, rapid administration of IV fluids may be required to control fluid and electrolyte balance. IV vasopressors may also be added in individuals experiencing shock due to volume depletion.  

The role of using IV mannitol to reduce neuronal edema can be controversial. Some studies have shown that administration of IV mannitol after rehydration may reduce acute neurological symptoms and prevent chronic recurrence of neurological symptoms. However, another study showed no difference between the administration of mannitol and IV saline.  

Individuals who experience symptomatic bradycardia may require atropine, a muscarinic antagonist, or temporary cardiac pacing to increase heart rate. In rare cases, respiratory failure may occur and could therefore require endotracheal intubation. Other medications may also be used acutely or chronically for symptomatic management and may include antiemetics for nausea and vomiting, acetaminophen or calcium channel blockers for headaches, and amitriptyline for paresthesias.