Food poisoning from fish: Ciguatera
The bottom line
Ciguatera poisoning is caused by eating fish that have themselves eaten fish contaminated with a toxin called ciguatoxin. Ciguatoxin cannot be detected by taste or appearance or prevented by cooking or freezing the fish. Treatment is available, but symptoms can last for months or years.
Prevention Tips
Avoid eating large fish, at or near the top of the food chain, as they are most likely to cause ciguatera poisoning.
Avoid foods known to trigger recurrence for several months after a diagnosis of ciguatera.
Use barrier protection to prevent sexual transmission in symptomatic ciguatera patients.
Breastfeeding mothers with active symptoms should consider pumping and dumping to avoid transmission of ciguatera to the baby.
This Really Happened
A 56-year-old woman ate barracuda while on vacation in Aruba. Eight hours after eating the fish, she developed nausea, vomiting, abdominal cramping, and itching. She then developed numbness around her mouth and a tingling sensation in her arms and legs. The following day, she noted that when she washed her hands under cold water, she felt as though her hands were “on fire.” She experienced the same feeling in her feet when she walked on a cold floor. She returned home to the U.S. and went to an emergency room, where ciguatera poisoning was diagnosed. At a follow-up visit with her primary care doctor 1 month later, she reported that nearly all her symptoms had resolved, except for the pain in her legs (from Patel & Jutzy, 2020).
What is ciguatera poisoning?
What you can't smell can't hurt you, right? Wrong! Eating some kinds of fish can cause some pretty unusual and dramatic symptoms.
Ciguatoxin is produced by a type of algae associated with coral reefs. Small plant-eating fish eat the algae, and they are then eaten by larger fish, which are eaten by yet larger fish, and so on up the food chain. This causes ciguatoxin to concentrate in larger fish. More than 400 species of fish are known to have caused ciguatera poisoning, but the most common are older, larger fish that have been eating contaminated smaller fish throughout their lives: grouper, barracuda, snapper, jack, mackerel, triggerfish, and others. Even though contaminated fish are from tropical and sub-tropical fish, ciguatera poisoning occurs anywhere these fish are shipped for consumption.
What are the symptoms of ciguatera poisoning?
Ciguatoxin usually causes symptoms within a few hours of eating the fish, but symptoms can be delayed for up to 24 hours. Patients can experience nausea, vomiting, diarrhea, muscle weakness, joint aches, headaches, dizziness, and low blood pressure. Ciguatoxin can also cause unusual neurologic symptoms because of swelling and dysfunction of the nerves. One characteristic and surprising symptom is "hot-cold reversal," in which hot items feel cold and cold items feel hot. Imagine drinking iced tea that feels warm! Some patients have reported numbness around the mouth and even the sensation that their teeth are falling out. Most people feel better in a few days, but in some cases, symptoms last for months or even years. Symptoms can recur after eating fish, alcohol, nuts, caffeine, chocolate, chicken, or eggs.
Most patients recover without treatment; however, those with significant dehydration require treatment with fluids and medications for nausea. Available treatment options for neurologic symptoms are not always effective.
How is ciguatera poisoning treated?
There is no specific way to prevent ciguatera, but avoiding eating larger tropical fish will reduce the chance of exposure to ciguatoxin. Recurrence of symptoms can be prevented by avoiding fish, alcohol, nuts, caffeine, chocolate, chicken, and eggs for several months after the diagnosis. Pain following intercourse with infected partners has been reported, suggesting the toxin could be sexually transmitted. For this reason, it is recommended to use barrier protection during intercourse with patients with active symptoms. Ciguatoxin is secreted in breast milk and has caused diarrhea and facial flushing in breastfed infants. Mothers should consider pumping and discarding their breastmilk if they are actively symptomatic.
Keep others safe, too. If you develop symptoms of ciguatera poisoning from fish from a store or restaurant, be sure to let the facility and your health department know. That might prevent someone else from becoming sick from eating the same fish.
For questions about ciguatera poisoning, or if you think someone is having a reaction to fish, use the webPOISONCONTROL® online tool to get help or call your poison center at 1-800-222-1222. Whether online or by phone, expert guidance is always free, confidential, and available 24 hours a day.
