What is ciguatera poisoning?

Ciguatera poisoning is a type of food poisoning. You get it by eating some types of fish. These fish feed in warm waters and can carry the ciguatera toxin. Many species of fish have been linked to outbreaks around the world.

Ciguatera poisoning is most common in:

• The Pacific islands
• The Indian islands
• The tropical Caribbean

In Australia, ciguatera toxin is more commonly found in fish that live in the warmer waters of:

• northern Queensland
• parts of the Northern Territory

More recently, a number of cases have been reported in New South Wales. These have mostly been associated with Spanish mackerel.

What are the symptoms of ciguatera poisoning?

Symptoms of ciguatera poisoning usually appear 1 to 24 hours after eating contaminated fish.

Symptoms can vary greatly, but may include:

• tingling and numbness in your fingers and toes, and around the lips, tongue, mouth and throat
• reversal of temperature sensation — so hot water feels cold or a cold drink feels hot
• joint and muscle pains with muscular weakness
• nausea, vomiting, diarrhoea or abdominal cramps
• headache, fatigue and fainting
• extreme itchiness — often made worse by drinking alcohol
• dizziness
• low blood pressure
• heart palpitations
• difficulty breathing in severe cases

These symptoms can last up to 3 months, and in some people several years.

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What causes ciguatera poisoning?

Ciguatera poisoning is caused by eating warm water fish that carry the ciguatera poison. Generally, these are fish that spend some or most of their life on coral reefs.

Ciguatera poison is caused by a naturally occurring marine toxin. This toxin is made by algae called gambierdiscus toxicus, which builds up in the food chain.

The toxin passed from small fish, which eat the affected algae, to larger predatory fish. When these larger fish are then eaten by humans, it can cause ciguatera poisoning.

There are more than 300 fish species that are suspected of causing ciguatera poisoning worldwide. Some of these fish are:

• Chinamanfish
• Coral Rockcod
• Coral Trout
• Giant Moray
• Giant Queenfish
• Kingfish
• Lined Bristletooth (Surgeon Fish)
• Mackerel (various, including Spanish Mackerel)
• Paddletail
• Pickhandle Barracuda
• Red Bass
• Red Emperor
• Spangled Emperor
• Trevally
• Tuskfish
• Wrasse
• Yellowtail Kingfish

How can I tell if a fish has the ciguatera poison?

You can't detect ciguatera toxin. It doesn't affect the appearance, smell or taste of the fish. So, fish that look fresh and visually appealing may be poisonous. This is partly because very low concentrations of ciguatera toxin can cause ciguatera poisoning.

Ciguatera toxin can only be found by laboratory tests. This test is very expensive so is only used in cases of suspected poisoning.

Currently, there is no way to test fish for ciguatera toxin before being sold.

Ciguatera toxin is heat stable. You can't destroy it by cooking or freezing the fish.

What effect will climate change have?

The algae that make ciguatoxins thrive on disturbed coral reefs. Coral reefs become disturbed through:

• coral reef bleaching
• extreme weather events such as cyclones

These events are predicted to increase, so it's likely that there will be more fish carrying the ciguatera poison. This will increase the risk of ciguatera fish poisoning.

When should I see my doctor?

See your doctor or go to your local emergency department if you develop ciguatera poisoning symptoms after eating warm water fish.

Do not eat any more of the fish.

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How is ciguatera poisoning diagnosed?

There is no test to diagnose ciguatera poisoning. Your doctor will ask you about your symptoms and food history.

If you have leftover fish, this may be tested to confirm ciguatera poisoning.

How is ciguatera poisoning treated?

There is no specific treatment available for ciguatera poisoning. However, there are treatments that can help ease your symptoms.

If you've had vomiting and diarrhoea, you may need extra fluids so that you don't become dehydrated.

If you are recovering from ciguatera poisoning, you should avoid:

• eating warm water ocean fish for at least 6 months
• alcohol for at least 3 months — alcohol can cause your symptoms to come back

Once you're better, only eat a small portion of fish — 200 grams initially. If your symptoms come back, see your doctor.

Can ciguatera poisoning be prevented?

To prevent ciguatera poisoning you can:

• avoid fishing in areas known to have ciguatera
• avoid eating fish that weigh more than 2.5kg and may have ciguatera
• eat small portions of warm water ocean fish — no bigger than 200g
• avoid eating the head, roe, liver or other viscera (guts) of warm water ocean fish as the toxin is more concentrated in these parts
• vary the type of warm water fish you eat

You can't remove ciguatera toxin from fish by freezing, cooking or cleaning it.

Complications of ciguatera poisoning

In severe cases of ciguatera poisoning, people can die because of respiratory paralysis. This is very rare.

Unfortunately, previous exposure to ciguatera toxin doesn't make you immune. In fact, it may increase your sensitivity to the toxin in future.

Repeated exposure to ciguatera toxin can make your symptoms worse or prolong your illness.

Resources and support

The Sydney Fish Market's Seafood Handling Guidelines lists:

• fish to avoid eating
• high risk fishing areas