8 hospitalized over ciguatera poisoning after seafood meals in northern Vietnam

The first family, part of a group of 14 traveling to Ky Anh Beach in Ha Tinh Province, consumed a seafood dinner on July 24 that included eel, shrimp, and oysters.

By the next morning, several members showed symptoms such as numbness in the mouth and tongue, muscle pain, joint fatigue, and digestive issues like diarrhea and chest discomfort.

That evening, four family members including a 55-year-old woman, a 51-year-old man, a 24-year-old man, and a 13-year-old boy were rushed to the hospital’s Poison Control Center, where they were diagnosed with ciguatera poisoning, a type of seafood toxin linked to reef fish.

Their conditions stabilized after one day of intensive treatment, said Nguyen Huy Tien, a doctor from the Poison Control Center.

Another case involved a family from Hai Phong City, who fell ill after eating a red snapper dish at home.

Roughly 1.5 to 4 hours after the meal, all four family members, including a couple and their two teenage children, experienced abdominal pain, vomiting, diarrhea, and widespread muscle cramps.

Two of them also showed signs of sensory disturbances.

Upon arrival at the hospital, all four were found to have abnormally slow heart rates and were also diagnosed with ciguatera poisoning.

Their condition is now stable, and they are expected to be discharged soon.

Nguyen Trung Nguyen, director of the Poison Control Center, warned that ciguatera poisoning is one of the most common types of fish-related food poisoning, yet it remains under-recognized.

Ciguatoxin originates from a microscopic algae species called Gambierdiscus toxicus, which is consumed by small fish that are in turn eaten by larger reef fish such as barracuda, grouper, red snapper, eel, parrotfish, amberjack, and even some types of sharks.

The toxin builds up in these larger fish and is not destroyed by cooking, freezing, or pickling.

“The most dangerous part is that the toxin is invisible. It has no color, taste, or smell,” Nguyen emphasized.

“Fish that carry the toxin may appear completely normal.”

Symptoms often emerge several hours to one day after consumption and include digestive issues like nausea, vomiting, abdominal pain, diarrhea; neurological symptoms like numbness, tingling in the mouth and limbs; and most notably, a reversal in temperature sensation that cold objects may feel burning hot.

Severe cases can involve a slowed heart rate, low blood pressure, and even life-threatening complications.

Neurological symptoms can linger for months or even years, significantly impacting quality of life.

To minimize risk, health experts recommend limiting consumption of high-risk reef fish species, especially their organs, where toxins accumulate most.

Farmed fish are considered safer, as their diet is controlled and does not include toxic algae.

“If people still want to enjoy these fish safely, farm-raised versions are a good alternative, though they cannot be as tasty as their wild-caught counterparts,” Nguyen added.

Anyone experiencing symptoms after eating reef fish should seek immediate medical care.