Firstly, on the subject of spiders, while there are thousands of spider species in Australia, very few of them are venomous. What’s more, their venom is intended to kill their prey so in inflicting a bite on a human, the quantity delivered is rarely enough to cause much harm. The exceptions include…
- The 40-odd species of funnel web spiders in Australia and probably the best known, the Sydney funnel web, the northern tree funnel-web and its smaller relative, the southern tree funnel-web. Mouse spiders are more active during the day, unlike most other spider species. They are often mistaken for funnel web spiders and the anti-venom has been found to be effective in mouse spider bites also.
- The Red back spider and the less venomous cupboard spider (similar body shape to the Red back but without red stripe)
FUNNEL WEB SPIDER
Funnel-web spiders are medium to large, shiny black or brown spiders, anywhere from 1 to 6 cms in body length with distinct fangs. They build funnel-shaped webs, to easily trap their prey and are mostly nocturnal. When a funnel web spider is disturbed, it will rear up and repeatedly strike with its fangs. The male Sydney funnel web spider is one of the deadliest spiders in the world and those powerful fangs can pierce a fingernail. Its venom is neurotoxic, attacking the human nervous system (it is more toxic to primates than mammals), and it can kill.
Where are they found?
Funnel web spiders are found from the Adelaide Hills in South Australia, and coastal and highland areas of Tasmania, Victoria, and up along the east coast to north Queensland; the Sydney funnel web lives in an area from Nowra to Newcastle, and inland to Lithgow. They prefer humid and moist sheltered spaces, digging burrows in the ground, under rocks, in holes in logs and trees or shrubbery, with the tree-dwelling species found as high as 30 metres. While their natural environment is in humid forests, shady areas of leafy private gardens are an attractive habitat. Funnel web spiders are often brought inside homes in firewood or after heavy rain during summer months the male may roam into a house in search of a female.
Bite symptoms build in intensity
- Very strong pain at the bite site, nausea, vomiting and abdominal pain, fast pulse and high blood pressure, difficulty breathing, tingling around mouth, spasms of the tongue, muscular twitching, profuse sweating, copious flow of saliva and tears.
- Without treatment and support measures, the envenomation eventually causes unconsciousness and death.
Treatment
Any bite inflicted by a big black spider in funnel web habitats should be treated as a funnel web bite. Keep the person still and calm while 000 (or 112) is called and first aid initiated. (For people who are deaf or who have a hearing or speech impairment, 106 is the number to call.)
Immobilisation pressure bandage of the bite site limb should be applied immediately and hold the limb down low - do not remove the pressure bandage. Time is of the essence so the person should be transported to emergency medical care where funnel web anti-venom is available. Administer CPR if the patient’s condition deteriorates.
Anti-venom is readily available in the area of the spiders’ habitat - no deaths have been reported since the venom became available in the 1980’s.
RED BACK SPIDER
Related to the Widow group of spiders found in other countries, the Red back spider may not always have that distinctive red or orange marking on its back. The female grows up to 2 cms in length and its bite can inject a highly toxic poison that (slowly) attacks the human nervous system; the smaller male’s fangs cannot penetrate human skin. Both the male and female are not considered aggressive and so bites are usually sustained when a hand or finger is accidentally pushed into a web. Around 2,000 bites are reported each year, however the Red back anti-venom, which has been available since the 1950s, is only used in more severe cases.
Where are they found?
Red back spiders are found Australia-wide in bush and urban areas, preferring a dark, sheltered and dry habitat around human habitation - in the house or garden such as sub-floors, empty receptacles (such as shoes and cans), letterboxes, roof eaves, garden sheds, around compost bins, in upturned flower pots or under rocks and logs. The spiders are more active in the warmer months of summer.
Bite symptoms
- Pain at the bite site is not immediate but may slowly build to be excruciating
- Sweating – starting locally at the bite site
Progression of symptoms with systemic envenomation include:
- Headache
- Nausea and abdominal pain
- Fever
- Hypertension
- Muscle pain and neck spasm
- Paralysis
Treatment
Healthy adults do not necessarily require urgent treatment for a bite (observation is recommended and go to hospital if pain lasts for longer than a few hours and simple pain relief is not helping), however children, the elderly, pregnant women and people with serious medical conditions should be monitored in hospital in case of complications.
First aid is as follows:
- Ice on the bite site and transport immediately to emergency medical care where, if needed, Red back spider anti-venom is available.
NOTE: Immobilisation of the bite site limb is NOT to be used as treatment for Red back spider bite.
“Necrotising Arachnidism”
This term is used for the development of ulcerating skin lesions that become necrotic following spider bites. Known to be caused by species of recluse spiders (genus Loxosceles) found mostly in North America.
In Australia, the White-tailed Spider (genus Lampona) has been unfairly tagged with this reputation. Blistering sores developing into necrotic ulcers have long been blamed on White-tailed spider bites without a bite being witnessed. The occasional finding of a white-tailed spider in the home following the development of such skin lesions has given this spider this reputation. However in a study of 130 patients with confirmed White-tailed spider bites, no cases of necrotic ulcers were observed (Isbister & Gray, 2003). Most bites from White-tailed spiders will result in burning pain, itchiness, redness and occasionally blistering.
NOTE: Immobilisation of the bite site limb is NOT to be used as treatment for white-tailed spider bites.
Other Australian spider bites and first aid
All other Australian spider bites should be treated symptomatically as well as applying ice or a cold compress to lessen the pain. Redness and blistering that develop at a bite site should be checked by your doctor as this could be due to a secondary infection – this applies for any insect/arachnid bite.
ALLERGIES
While some people may have a local reaction to a spider bite – pain, redness and swelling develop soon after - it will usually settle with the direct application of a cold compress directly over the bite site for 15 minutes (reapplied when needed), analgesics and antihistamines. However there have also been instances of severe allergic responses to spider bites – anaphylactic shock – which can occur within minutes and must be treated as a medical emergency. As per the Australian Resuscitation Council, signs of anaphylaxis may include:
- difficult / noisy breathing
- wheeze or persistent cough
- swelling of face and tongue
- swelling / tightness in throat
- difficulty talking and /or hoarse voice
- persistent dizziness / loss of consciousness and / or collapse
- pale and floppy (young children)
- abdominal pain and vomiting
- hives, welts and body redness
Managing anaphylaxis involves calling 000 for urgent assistance and commencing CPR if needed. In the event of a known allergy, administer an Epipen, if available. More on treating anaphylaxis from the Australian Resuscitation Council.
PREVENTION OF BITES
Best way to avoid being bitten by spiders is to:
- Leave them alone
- Use gloves when gardening, clearing out garden sheds and removing building rubble from homes.
- Reduce rubble/debris from inside and around the house to limit spiders’ preferred habitats
- Inspect or knock out any shoes/clothing left outside before using
Despite all of the above, in most cases spiders are harmless and there is no doubt they are crucial in the control of insect populations. Awareness is the key for this ‘ancient source of fear and fascination’.
References:
Australian Museum: https://australian.museum
Australian Reptile Park: https://reptilepark.com.au
Live Science: https://www.livescience.com
Science direct: https://www.sciencedirect.com
Spiders.com.au: https://www.spiders.com.au
Royal Children’s Hospital: https://www.rch.org.au/clinicalguide/guideline_index/Spider_Bite
Australian Museum: https://australian.museum/learn/animals/spiders/cupboard-spider/
Australian Resuscitation Council: https://resus.org.au/
The Conversation: https://theconversation.com/the-truth-about-spider-bites-in-australia-theyre-unlikely-to-eat-your-flesh-75836