Envenomation in Australia

There are lots of venomous creatures in Australia. This is intended to be a quick reference to the management of lifethreatening envenomations from these creatures. I must thank Struan Sutherland for providing most of the information and John Loadsman for help with development of these pages:

At the end of this page I have contact details for other Australian envenomation information resources.

Ashley Ng has provided, in Palm Reader format, an eBook of these pages: Snake Bite in Australia.pdb (170k)


Venomous Australian creatures

Australia is unfortunate in having many species of venomous creatures, both on land and in the sea, including:

  • 38 terrestrial snakes and 23 sea snakes.
  • 22 spiders, 4 ants, the honey bee, 3 wasps, 2 beetles(!), 6 scorpions, 2 caterpillars, centipedes, millipedes, mosquitoes, sandflies, thrips and other insects.

The platypus and echidna both have venomous defence systems.

In the coastal waters there are 2 blue-ringed octopuses, 7 jellyfish, cone shells, 2 stonefish, 21 other fishes including the flathead, the Port Jackson shark, 11 rays, starfish including the crown of thorns, corals, anemonies, urchins, stinging sponges, marine worms, leeches, frogs and toads.

As far as snakes go, Australia is home to the ten most lethal in the world. Struan Sutherland reckons that of the world's top 25 venomous snakes, Australia has 21. After considering venom toxicity, average yield, and aggressivness, he ranked the North American diamond-backed rattlesnake at number 25 in the world, with the Indian cobra and African black mamba 12th and 13th respectively! Peter Mirtschin's paper provides more detail on relative venom toxicity and Brian Bush provides a different perspective.


Venom Actions

Many venoms have multiple components or toxins that lead to a complicated clinical picture. Most affect autonomic and skeletal nerves but also may interfere with other parts of the nervous system and smooth muscle.

Neurotoxins

Neurotoxins are responsible for the majority of symptoms following Australian snake bites.

Postsynaptic toxins

All Australian snakes have at least one low molecular weight postsynaptic neurotoxin. These snake toxins block post-synaptic acetylcholine receptors causing paralysis (and sometimes hypotension), and like alpha-bungarotoxin, a pure postsynaptic blocker from the Asian krait, are also found in cone shell venoms. They are rapid in onset and their action often causes the prodominant clinical picture. Fortunately, these effects are usually rapidly reversed by anti-venoms.

Abnomalities of Acetylcholine Release - presynaptic toxins

Alpha-latrotoxin from the Red Back spider depletion of presynaptic vesicles, resulting in patchy muscle paralysis and catecholamine release. Snake neurotoxins usually prevent vesicle recycling leading to paralysis with characteristic EM images at the presynaptic region, while Tick venoms have similar actions but no EM changes. These act more slowly and their effects are more difficult to reverse than the post-synaptic toxins.

Blockade of Nerve Conduction

Tetrodotoxin is the classic example. Found in blue ringed octopus saliva and the flesh and organs of puffer and toad fishes, TTX prevents action potential propagation by Na+ channel blockade. Not common in snake venom.

Spontaneous Action Potentials

Atraxotoxin from the Sydney Funnel Web spider causes gross muscle twitching, catecholamine release and glandular hypersecretion due to development of uncontrollable spontaneous action potentials in skeletal and autonomic nerves.

Myotoxins

These are common in Australian snake venoms, and may cause rhabdomyolysis and potential for renal failure, in particular after a bite from the beaked sea snake and the king brown (mulga), rough scale, red bellied black, lowland copperhead, tiger and small eyed snakes.

Haematological toxins

Coagulation disturbances following snakebite are not uncommon. Strongly coagulant venoms may produce DIC, and while severe haemmorrhage is uncommon, fatal cerebral haemmorrhage and substantial bleeding from, for example, pre-existing gastric erosions, may occur. The relative rarity of this is due to the fact that Australian snake venoms do not possess toxins capable of damaging the vessel wall.

Tiger snake venom activates prothrombin in presence of Factor V and Calcium, whereas the western brown, brown, dugite, and taipan snakes directly activate prothrombin and may result in very low fibrinogen levels and severe biochemical coagulopathy.

Haemolysis is rare (usually clinically insignificant; seen only in severe box jellfish, and black and copperhead snake envenomation).

Nephrotoxins

The eastern brown snake venom may contain nephrotoxins.

Locally acting toxins

Snake venoms include hyaluronidase, cytotoxins, and other low molecular weight enzymes; these result in local pain, oedema, necrosis, and possibly headaches and systemic myalgia.

Marine venoms commonly cause severe pain (stonefish, ray and fortescue in particular), and, if severe, ischaemia, cyanosis and necrosis.

The bite of several spiders, with the the white tailed spider being most commonly implicated, may be associated with 'necrotising arachnidism', where the area around the bite becomes oedematous and necrotic over a day or two - otherwise necrosis is uncommon in Australian envenomations.


Resources

Members of the public who are seeking information about how to identify and deal with spider, snake or insect problems in their home environment should contact their local pest inspector.

The Australian Venom Research Unit at the University of Melbourne was a very comprehensive resource for evnomation related issues but their web pages are not available any more. If you are a physician and are caring for a patient with severe envenomation, or need further information about the management of necrotising lesions after spider bites, you could contact them by phone (1300 760 451 or +61 3 8344 7753), fax (+61 3 9348 2048) or by e-mail. See their contact details page if you need more info.

Antivenoms are manufactured and distributed in Australia by CSL's Human Vaccines division. Freely available information includes pictures of snakes and advice for patients. Full product information for physicians is restricted to those registered with MedEServ in Australia (which includes all Australian anaesthetists - use your ANZCA password, enter via the CSL NET link at the top) or those who have registered with CSL. The CSL Antivenom Handbook is available in html format on the Adelaide Womens and Childrens Hospital Toxinology.com site, which also provides a lot of other useful information.

Untested suggestions that the local application of high voltage DC electricity to snake or spider bites may reduce pain or prevent envenomation should be viewed with caution. There is no scientific basis for this approach, which is based on hearsay from non-lethal bites. Any electricity that could denature venom proteins would almost certainly damage your own tissues. It is highly likely that failure to implement appropriate first aid while messing around with electrical gadgets may be fatal.

Some people ask about precautions before going out in places where snakes exist. The best idea is to know their habits, avoid them where possible, never try to kill them or pick them up, wear appropriate clothing, carry a first aid kit and know what to do, don't travel in bushland alone, carry a means of contacting the outside world, and so on. If you must deal alone in the bush with snakes or spiders you could try to obtain some freeze-dried antivenom, some sterile water and a syringe from a local doctor. Most likely you'd never need to use it.

If you are undertaking scientific research in the taxonomy of venomous Australian creatures, try contacting the Australian Museum.

Struan Sutherland has recently published a book of his memoirs titled "A Venomous Life" (available from Hyland House Publishing, 387 Clarendon Street, South Melbourne, 3205 Australia). It's a great read!

Some nice spider photos and information are available at Steve's Aussie Spider Pics.

The photos in these pages are the work of Peter Mirtschin who is the proprietor of Venom Supplies. They have a web site detailing their services and which contains some interesting info on the various constituents of some venoms. The additional linked pictures are taken from the Antipodes Design publication Dangerous Snakes and Spiders of Australia (Little Books of Australia) and are copyright. They are used with the permission of the publisher. The photographers were Geoff Swan, Brian Bush, John Weigel (Australian Reptile Park), M. R. Gray (Australian Museum) and R. E. Mascord (Australian Museum).


Last updated Saturday, April 23, 2016
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