Ciguatera poisoning

Ciguatera poisoning is caused by eating certain types of reef fish found in warm tropical waters.

These fish eat a type of algae called Gambierdiscus toxicus, which makes ciguatoxins.

Small fish that eat this algae are eaten by bigger fish, and then they’re eaten by even bigger fish.

Each time this happens, the toxin in the fish increases, and it’s the large fish that are most likely to make you sick.

The toxin can’t be removed by cleaning or cooking the fish.

In Australia, about 150 cases of ciguatera poisoning occur each year.

Where is it found

Fish with ciguatera are found in the coral reefs of tropical and sub-tropical waters.

In the Northern Territory (NT), these fish are in the Gove and Groote Eylandt areas, such as:

• the south end of Bremer Island
• East Bremer islets
• Bonner Rocks
• Miles Island
• Cape Arnhem area
• Nhulunbuy (Gove)
• Connexion Island off Groote Eylandt.

They may also be in other NT waters.

Fish species with ciguatera

There are more than 300 fish species that have been suspected to cause ciguatera poisoning.

These include:

• chinamanfish
• tripletail maori wrasse
• humphead maori wrasse
• red bass
• paddletail
• giant moray
• pickhandle barracuda
• coral rockcod
• coral trout
• kingfish
• mackerel (various including spanish mackerel)
• giant queenfish
• red emperor
• reef cods
• lined bristletooth (surgeon fish)
• spangled emperor
• trevally
• tuskfish.

Symptoms

Symptoms can appear 3 to 6 hours after eating fish with ciguatera. But they can also start up to 30 hours later.

They can appear as food poisoning symptoms such as:

• tiredness and lethargy
• nausea and vomiting
• diarrhoea
• stomach cramps.

Other typical symptoms are:

• joint and muscle pain and weakness
• tingling or numbness around the lips, in the hands or feet
• severe itching, made worse by drinking alcohol
• headache
• feeling that teeth are loose or aching
• reversal of temperature sensation:
  • hot water feels freezing cold
  • cold drinks feel hot
• heart palpitations
• low blood pressure and slow pulse
• difficulty in breathing in severe cases.

Some of these typical symptoms can last up to 3 months and in some cases, several years. They can be made worse by stress or drinking too much alcohol.

Diagnosis

There is no test for ciguatera poisoning. You will be diagnosed based on your symptoms and food history.

Sometimes, leftover fish is sent to laboratories for research purposes. The results take time and are not relevant for your diagnosis.

Treatment

As soon as your symptoms start, you should see your GP or nearest health centre for treatment.

Treatment will not get rid of the toxin but it will ease your symptoms.

If you’ve experienced vomiting and diarrhoea, you may become dehydrated and need extra fluids.

It’s rare to die from ciguatera poisoning. This happens only in very severe cases from respiratory paralysis or cardiovascular shock.

You are not immune if you’ve already had ciguatera poisoning. You may even be more sensitive to the toxin the next time you get it.

Prevention

To prevent ciguatera poisoning, you should:

• not fish in known ciguatera areas
• avoid eating fish species with suspected ciguatera that weigh more than 2.5kg
• eat small portions of warm water ocean fish, no bigger than 200g
• not eat the head, roe, liver or other viscera (guts) of warm water ocean fish, as the toxin is concentrated in these parts.

You must also remember that any fish spoilage can give you food poisoning. Fish must be cleaned and stored at safe temperatures.

Information for health professionals

To find out more go to the NT Health website.

Contact

For more information, contact your nearest Public Health Unit on the Department of Health website.