Ciguatera Poisoning

What is Ciguatera

Ciguatera refers to a rare foodborne illness affecting the muscular, digestive, or neurological system that is caused when ciguatera poisoning contaminated reef fishes are consumed. (6)

What Type of Toxin is Ciguatera

Ciguatera is a biological toxin, produced by the microalgae called Gambierdiscus that inhabit coral reefs.

Ciguatera Fish Poisoning Signs and Symptoms

Initial neurological symptoms, affecting lips, tongue, hands or feet, and beginning 30 minutes after consumption may involve:

• Itching
• Tingling
• Numbness

The only neurological symptom found in children is irritability.

Other symptoms (neurological, GI and visual), occurring between 6 to 17 hours may include:

• Abdominal cramps
• Vomiting
• Diarrhea
• Nausea
• Painful defecation
• Pain and loosening of teeth
• Muscle and joint pain
• Reversal of hot and cold sensation
• Weakness
• Blurred vision
• Abnormal sensitiveness to light
• Tremendous sweating
• Metallic taste
• Excessive salivation
• Dizziness
• Restlessness
• Wheezing

Cardiac symptoms may include:

• Blood pressure fall
• Slow or fast heart rate

The symptoms indicating severe ciguatera poisoning are:

• Chills
• Shortness of breath
• Tearing of eyes
• Skin rashes

Causes

This nonbacterial fish poisoning usually occurs as the toxin accumulated in various parts of a reef fish, on consumption, activate certain channels on the body cells, called voltage-gated sodium channels, thereby resulting in a host of symptoms. (9)

In What Kind of Food is Ciguatera Toxin Found

The toxin is found in carnivorous reef fishes such as barracuda, blackfin snapper, and moray eel as well as herbivorous and omnivorous fishes like red snapper, parrot fish or surgeonfish.

Risk Factors

Men and women of all age groups may be affected, but the primary ones are travelers to endemic regions as well as people living in tropical and subtropical countries, chiefly the Caribbean and Pacific regions. Further, pregnant women suffering from ciguatera poisoning, may transmit the toxin to the fetus trough the placenta, while infected breastfeeding mothers, may pass on the toxin to the baby through breast milk.

Complications

• Dyspnea
• Muscular paralysis
• Orthostatic hypotension
• Coma
• Bradycardia
• Respiratory arrest

Diagnosis and Tests

After an initial assessment of symptoms and dietary history, some nonspecific tests are done such to check for elevated levels of mild creatine phosphokinase (CPK) and lactate dehydrogenase (LDH).

Another nonspecific test, Visual Contrast Sensitivity (VCS) is carried out to determine the patient’s ability to detect the colors white, black and gray, which is often impaired by the neurotoxin.

Since these tests may indicate other types of neurotoxic poisoning such as botulism or shellfish poisoning, at times, a conclusive ciguatera toxin analysis may be done by subjecting the contaminated fish for diagnostic testing.

Differential Diagnosis

• Botulism
• Mushroom toxicity
• Organic phosphorous compound and carbamate toxicity
• Shellfish toxicity
• Tetrodotoxin toxicity
• Scombroid toxicity
• Guillain-barré syndrome

Treatment and Management

There is no specific treatment procedure available for the disorder. However, some modern methods may be recommended, involving:

• Gastrointestinal decontamination using activated charcoal, that may be done 3 to 4 hours after ingestion of the charcoal to absorb the toxin (3)
• Immediately pumping out all the stomach content (gastric lavage)

Since no antidote for the disorder is available, following certain procedures at home may help. According to some studies, vomiting within 3 to 4 hours of consumption of the infected fish may help. Hydration of the patient is also done to maintain the loss of his fluid balance due to vomiting.

Treatment of Associated Conditions

Medication

• Osmotic diuretics such as mannitol (Osmitrol) to effectively decrease the severity and span of neurological symptoms
• NSAID’s and acetaminophen ( eg.Tylenol) to decrease pain
• Amitriptyline (Elavil, Endep) and gabapentin (Neurontin, Gralise, Horizant) to lessen neural pain symptoms
• Diphenhydramine (Benadryl) and hydroxyzine (Atarax, Vistaril) to provide relief in itching (3)

How to Prevent Ciguatera Poisoning

It is important to note that the ciguatera toxin neither changes the fish’s taste, smell and texture, nor does it get destroyed by cooking. Hence, the preventive measures that can be followed are:

• Restraining from eating reef fish
• Avoiding the head, liver, and intestines of small reef fish, where the toxin may concentrate

Incidence and Prevalence

The incidence of ciguatera fish poisoning is estimated to be more than 50,000 cases per year. Amidst this, 3 out of 100 travelers to high endemic areas may have this ailment. According to certain reports, global warming resulted due to climate change, seems to be one of the reasons, responsible for an increase in ciguatera fish poisoning at present.

Prognosis and Life Expectancy

Most people suffering from this disease recover slowly, with relapsable symptoms that may induce long term effects for nearly twenty years. The slow releasing nature of the toxin may be a primary reason for recurrence. Death may occur in rare cases (0.5%).