Symptoms appear after a few hours of eating fish
According to information from the group of tourists, on the evening of March 7, the group had a meal at a local restaurant with seafood dishes including eel, tiger shrimp and clams. However, only a few minutes to about 3 hours after the meal, many people began to show abnormal signs.
Initial symptoms include sore throat, mouth, numb lips and tongue. Then, manifestations spread throughout the body such as muscle aches, weakness in limbs, muscle weakness, dizziness, low blood pressure, nausea, vomiting, abdominal pain and loose stools.
Some patients also feel chest tightness, a lot of fatigue, and a sharp pain when touching cold water. When defecating, they also experience pain and discomfort in the anus. Notably, even the person who eats the least – only about two pieces of fish – also develops symptoms.
Recognizing abnormal health conditions, the tourists were given first aid at a local medical facility. Among them, 6 people were transferred to the Poison Control Center, Bach Mai Hospital on March 8 for further monitoring and intensive treatment.
After examination and exploiting epidemiological factors, doctors determined that this was a cluster of ciguatera poisoning cases due to eating eels containing ciguatoxin toxin.
Dangerous toxins, not destroyed when cooked
Dr. Nguyen Trung Nguyen - Director of the Poison Control Center, Bach Mai Hospital - said that ciguatera poisoning is the most common form of sea fish poisoning, even more common than pufferfish poisoning, but in reality it has not been noticed by many people.
Ciguatoxin toxin originates from a type of microalgae called Gambierdiscus toxicus living in seawater. Small fish eat algae, large fish eat small fish, and through this food chain, toxins will gradually accumulate in the bodies of large fish living in coral reefs.
Many fish species may contain ciguatoxin toxins, especially large fish such as hemibagrus, perch, mackerel, grouper, eel, bowfish, shark...
What is worrying is that ciguatoxin toxin is completely colorless, odorless, tasteless and not destroyed by conventional processing methods such as cooking, freezing or salting, drying. A poisoned fish still has a completely normal appearance, so it is very difficult to recognize.
Ciguatera poisoning can cause many different groups of symptoms.
Regarding digestion, patients may experience nausea, vomiting, abdominal cramps and diarrhea.
In terms of nerves, patients may experience numbness, burning sensation when exposed to cold, itching like allergies but no skin damage, muscle pain, muscle weakness or muscle paralysis. In severe cases, respiratory muscle paralysis can lead to respiratory failure and risk of death.
A fairly characteristic symptom of ciguatera poisoning is hot-cold sensation disorder: when touching cold water, the patient feels a sharp pain or burning sensation.
In addition, cardiovascular complications such as low blood pressure or slow heartbeat can also occur and be life-threatening if not treated promptly.
Notably, in some cases, neurological symptoms can last for months, causing discomfort and significantly affecting the patient's quality of life.
Currently, there is no specific antidote to ciguatoxin. Treatment is mainly symptomatic treatment, ensuring breathing, stabilizing heart rate and blood pressure, and monitoring complications.
According to Dr. Nguyen Trung Nguyen, prevention is still the most important measure. People should limit eating a lot of natural marine fish at high risk, avoid eating fish organs because this is where many toxins accumulate.
Be cautious with fish caught in coral reefs. If you want to use these fish, choosing farmed fish may be safer because the feed of farmed fish is controlled and does not contain toxins from seaweed". Dr. Nguyen Trung Nguyen recommends.
6 patients treated at the Poison Control Center, Bach Mai Hospital have stabilized their health and been discharged.
