Disease Information Sheets

Spider bites
Introduction

Only a few dozen of the 34,000 spider species are considered a threat to human health, and they are present in all but the coldest parts of the world. The majority of spiders that pose any threat to humans produce only a mild local reaction similar to a wasp sting, and at worse a brief illness. A very small number of species may cause a severe local reaction and/or more severe illness. Spiders very rarely transmit human diseases. Even in Australia, home to the redback spider and potentially lethal funnel-web spiders, most bites are trivial.

 

How common are they?

Spider bites are common in most parts of the world, but the vast majority cause only minor effects. The most significant danger posed by spider bites may in fact be from over-aggressive first aid and medical treatments, perpetuated by exaggerated fear and over-emphasis of extremely rare cases of significant illness and death.

 

Are travellers and/or expat workers at risk?

Not really. Travellers are at the same level of risk as the resident population. The absolute risk to health posed by spiders is very low.

 

What is the illness?

The offending spider is rarely seen or identified, so it is important to consider whether the symptoms assumed to be due to a spider bite could actually be due to something else, for example local skin infection, tick-borne diseases that cause skin lesions, bites and stings by other creatures, or a splinter or other buried foreign body. If the patient is experiencing systemic signs and symptoms, other possible causes to consider include snake or scorpion bite/sting, pesticide toxicity, generalised infection or one of the many causes of abdominal pain, depending on the symptoms.

 

Signs and symptoms are usually restricted to central puncture marks, blisters or ulcers, redness or pallor, bleeding or hardening, loss of sensation or tenderness and maybe red streaks progressing up the limb. Very rarely the bite may cause a systemic (whole body) illness such as a whole-body rash, sweating, raised heart rate and/or facial swelling. In this case, the patient should seek urgent medical attention.

 

How is it prevented?
  • Inspect and shake out clothing, shoes, towels and equipment before use

  • Wear long-sleeved clothing and trousers, gloves, boots etc if handling stacked or undisturbed piles of materials

  • If storing/stacking items, push them together so there are no cracks for spiders to crawl into

  • Remove and reduce rubbish and debris in and around your camp

  • Store items in sealed plastic bags or containers that are spider-proof

 

How should it be treated in the field?

The most debilitating symptoms associated with the bite may be fear and anxiety - you should provide reassurance that the vast majority of bites are not dangerous. Do your normal ABCs of first aid, and monitor vital signs. Wash the bite with soap and water. Local pain can be relieved by applying a cold pack. If the pain is severe, immobilise the whole limb without applying pressure to the wound. Do not attempt to extract the venom or use a tourniquet. Phone a doctor for advice, and be prepared to take the patient to medical care.

If you can identify or catch the culprit (without it biting again), do - this will assist with any medical care required.

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