Stonefish Envenomation

Stonefish are widely distributed throughout tropical, marine waters of the Indo-Pacific with two potentially deadly stonefish in Australian tropical waters. The Estuarine Stonefish (Synanceia trachynis)and Australian Reef Stonefish (Synanceia verucosa) are recorded from much of the Great Barrier Reef in northern Queensland to far northern New South Wales.

The Reef Stonefish is the most dangerous venomous fish in the world. The unattractive, squat fish is well camouflaged against ocean floor debris and coral looking like an encrusted rock or a piece of coral. There are numerous erect spines along its dorsal fin that act like syringes which deliver highly toxic venom. They usually live on rubble or coral sea beds, often under rocks or ledges, but are also known to be able to bury in sand using their large pectoral fins.

Envenomation typically occurs when they are inadvertently stepped on or picked up mistakenly.

Stonefish venom

The multicomponent venom has neurotoxic and myolysin effects. It also has direct effects on the heart and blood vessels.

Symptoms of envenomation

The first and most dramatic sign of stonefish envenomation is severe, intractable pain followed by localised swelling at the puncture site. Often a dorsal spine will break off and remain embedded in the affected body part. Isolated reports of systemic envenomation involving dizziness, nausea, vomiting and progressing on to collapse and breathing difficulties.

First Aid in the field

The principles of first aid in the field are to minimise the spread of venom into the blood stream while awaiting transfer to expert medical care. In addition to General First Aid principles, any suspected victims of Stonefish envenomation should have the affected limb immersed in hot water (not to hot to burn the skin)

No attempt should be made to capture or pick up the fish.

Antivenom

CSL Stonefish  Antivenom is specific for neutralising the venom of the Synanceia verucosa Stonefish but is also effective against thetrachynis subspecies. The antivenom is produced from horse serum.

The antivenom should only be administered if there is clear evidence of symptoms of envenomation. It may be administered in the field but must be administered by experienced medical personnel and all victims of envenomation require transport to hospital. The risk of anaphylaxis to the antivenom is moderately high and although pretreatment with adrenaline and antihistamines is not indicated, capacity to manage anaphylaxis must be available.

The antivenom is administered as an intramuscular injection. The initial dose is one ampoule for every two visible spine puncture sites.. The dose should be repeated as required according to response to treatment.

Following antivenom

• The tetanus immunisation status of the victim should be checked and updated if necessary
• The victim should be observed for a minimum of 12 hours following full resolution of symptoms of envenomation
• The victim should receive advice on the potential to develop serum sickness