CASE 1: THE CHILD WHO ‘DIED’
A 2-year-old Vietnamese girl presented in dramatic circumstances to the casualty department of a country hospital when I was on duty. She was apnoeic and required manual ventilation by the ambulance officers. They claimed that they went on a call expecting to find a pregnant woman in labour, but instead they found a young Vietnamese woman with her daughter ‘asleep’ in her arms. They noticed that the child was not breathing and thought she was dead, but she had a full pulse. They promptly began artificial ventilation, her colour improved and she remained in a stable condition during the ambulance trip.
On examination in casualty she had a normal colour, a full bounding pulse, normal heart sounds and blood pressure—but no spontaneous respiration. Neurological assessment revealed generalised hypotonia, areflexia (including plantar reflex), fixed dilated pupils and no response to painful stimuli. There were no other abnormal findings in any other system and no evidence of injury. A blood glucose estimation (glucometer) was 6 mmol/L.
The child was promptly intubated and cardiac monitored, and an intravenous line was inserted.
The language barrier made it difficult to obtain an accurate history. However, I was able to ascertain that shortly after eating lunch the child staggered about as though ‘drunk’ and eventually fell to the floor and stopped breathing.
My initial diagnostic hypotheses included aspiration or an intracerebral catastrophe, but I realised that the clinical information did not support this reasoning. On further questioning of the relatives I learned that for lunch the family had eaten a fish the father had caught off the pier of a Victorian coastal town.
I diagnosed tetrodotoxic fish poisoning due to eating a toadfish (‘toadie’). These poisonous fish are found around the coast of Australia. A quick reference to a text on toxic marine animals (Sutherland, 1983) provided information that the poisoning is characterised by progressive ataxia leading to respiratory paralysis, making it appear that the patient is dead. This did not explain why the parents were spared. Since the toxin is reported to concentrate in the liver and ovaries and only in small amounts in muscle, I considered that the child was served the offal and the parents ate the flesh.
The child was transferred to the intensive care ward of the Royal Children’s Hospital, Melbourne, where she made a full recovery after three days. The prognosis for respiratory arrest in children is apparently excellent.
In Japan the toadfish (fugu) is a delicacy, but it can only be prepared by specially licensed chefs who manage to remove most of the tetrodotoxin from the flesh, although the toxin cannot be removed by washing or by prolonged cooking. Apparently, part of the enjoyment of eating the fish is the tingling sensation felt on the tongue due to small amounts of the toxin. There are several deaths a year in Japan due to ingestion of this fish. Captain Cook almost died in 1774 after sampling a little of the roe and liver of a toadfish in New Caledonia.
CASE 2: A ‘TINGLING’ EXPERIENCE
A 40-year-old businessman, holidaying in Queensland, presented with extreme weakness, exhaustion and strange ‘numb’ and ‘tingling’ sensations around his mouth and in his hands, following an episode of diarrhoea, abdominal pain and vomiting. He gave a fascinating history of how he and his two mates went on a fishing trip near Cairns when they caught some large Spanish mackerel. They said they experienced a strange, cold, tingling feeling in the hands while cleaning the fish.
Five hours after eating one of the fish all three developed what they considered to be a ‘gastric’ attack with diarrhoea and vomiting. After this settled the patient was aware of aching in the joints and muscles as well as the tingling sensations. He said he also experienced a strange burning painful feeling when his hands were placed in cold water. ‘I can’t go swimming in the sea, Doctor—it feels terrible.’ On examination he was afebrile and no specific abnormality could be found.
On review two weeks later he still felt weak and anorexic. He had pruritus of the skin and mild tingling sensations that became worse when exposed to cold factors such as water or ice-cream.
The patient has ciguatera poisoning due to eating a fish containing ciguatoxin. The problem can occur in all tropical and subtropical sea water to 30° latitude. The differential diagnosis is bacterial food poisoning, but this produces the rapid onset of gastrointestinal symptoms without peripheral neurological effects.
DISCUSSION AND LESSONS LEARNED
Toxic reactions to eating fish should be considered if patients exhibit unusual neurological symptoms and signs including ‘tingling’ sensations of the extremities and respiratory paralysis.
Obviously people should be warned about eating toad or ‘puffer’ fish and should avoid eating large carnivorous fish in some tropical waters. Moray eels should never be eaten, nor should the viscera or gonads of any tropical fish.