White-tail spiders: a web of misconceptions

Linley Boniface is to be congratulated for her humorous take on the prevailing hysteria around alleged “white-tail spider bites” (Dominion Post 9 March).

An Australian, Dr Geoff Isbister, has done the most to debunk the belief that this Australian immigrant has been responsible for everything from limb amputations to ulcers and skin grafts. A careful scientific study has shown that a white-tail spider bite causes a small and painful red mark which is gone in a few days. The Isbister study required evidence of a bite as well as expert identification of the spider which had to be available for examination.

I found another false belief that white-tail spider bites possess a special toxicity because they feed on other spiders in the home, particularly the ‘Daddy Long-legs’. There is no evidence for this and when I was corresponding with Dr Isbister he wittily referred to this belief as a “myth within a myth”.

In the course of my work in the Emergency Department I have seen dozens of strange skin lesions which had been attributed to white-tail spider bites. I have only seen one case that I accepted as being a genuine bite. A young woman put on her slipper and felt a sudden sharp pain. When she removed the slipper a spider dropped out which she identified as being a white-tail. There was a small red mark. No treatment was necessary and when she phoned me a few days later the injury had completely resolved. Note that this account does not meet the strict criteria of the Isbister study but the outcome is similar.

Juicy Fruitless?

“Fruit juices with added extras such as herbal supplements may actually be harmful” – so says the Marlborough Express (10 March). Such products are aggressively marketed by advertisers using brand names such as ‘Kickstart’, ‘Energy Lift’ and ‘Green Recovery’. Perhaps it was this product that helped the Green Party gain an extra seat in the last election!

An Australian consumer group (Choice) found that herbal extras did not actually contain enough extracts to have any meaningful health effect and some could have been dangerous. The claims of some were simply wrong. For example, one product claimed to contain greater than 30 percent of the daily omega three fats requirement. It actually contained only eight percent of the recommended daily dose for men.

Choice’s advice is timely: “it’s best to stick to the whole fruit or vegetable.”

Internet mythology

Mike Bradstock writes: “I am a bit concerned by the number of anonymously written emails I get from well-meaning people telling me how to do an instant stroke diagnosis and suchlike. Have you encountered this sort of thing and is any of it well founded?”

Well, yes. I get such advice all the time. For example, if you feel chest pain and loss of consciousness coming on, cough and you can ward off the effects of a cardiac arrest! Here is another example: “For those who like to drink cold water, this article is applicable to you. It is nice to have a cup of cold drink after a meal. However, the cold water will solidify the oily stuff that you have just consumed. It will slow down the digestion. Once this ‘sludge’ reacts with the acid, it will break down and be absorbed by the intestine faster than the solid food. It will line the intestine.

“Very soon, this will turn into fats and lead to cancer. It is best to drink hot soup or warm water after a meal.”

The internet provides an opportunity for ignorant people to propagate such nonsense (alimentary errors?). It reminds me of that joke – if you give several million monkeys a typewriter and leave them to bash away randomly, one might produce the works of William Shakespeare. Thanks to the internet we know that’s not true.

That is the paradox of the internet – it pops up a lot of rubbish but at least you have the means to instantly check anything that has been sent to you. There can be nothing more satisfying than hitting “Reply to all” with a link identifying something as an urban legend.


The internet is very useful in the health sector and I often encourage people to use it to check things for themselves. After offering health advice and sensing that I am not believed I often say to people, “You don’t have to believe me – check for yourself and you will see I am telling you the truth.” As well as just dealing with illness I believe that doctors have a duty of care to educate their patients. Instead of endorsing ACC claims for ‘white-tail spider bites’ doctors should be telling patients about the Isbister study. Some web-based applications have been shown to be better than doctors in diagnosing the cause of abdominal pain. Of course the internet can also be a cause of anxiety for people who endlessly trawl websites looking for diseases that they might have. This has been labeled ‘cyberchondria’ and is typified by an addiction to internet symptom diagnosis.

Edward Shorter (From Paralysis to Fatigue: A history of psychosomatic illness in the modern era) predicted that we were entering a psychosomatic era and the internet is perfectly placed to play its part in fostering abnormal illness beliefs such as RSI, GWS, MCS and so on.

Hypochondriasis will always be with us and whatever the damage done via cyberchondria I believe on balance that the internet is a hugely beneficial technology for medicine. I use Google nearly every day to check unusual acronyms, drug doses and current evidence-based treatments.

The cyberchondria article mentioned the dread doctors feel when patients walk into a consulting room with copious web printouts. I seldom experience this but I did once have a mother offer a rare web-based diagnosis for her sick child. She was right! The annoying thing was that the initial presentation was atypical and after the child was discharged from hospital she refused to pay her bill because she claimed the diagnosis ought to have been made at the first consultation.

Vitamin C Quackery

The NZ Family Physician (Vol 35 number 5, October 2008) is now defunct and I for one will not miss it. It had become a hackneyed apologist for quackery and the last issue lived up to this reputation by publishing an infomercial for a quack vitamin C clinic posing as an original scientific paper (www.rnzcgp.org.nz/nzfp-october-2008/).

A link soon appeared on the vitamin clinic website (www.camltd.co.nz)

The NZFP has been replaced by the Journal of Primary Health Care and I am very pleased to report that the editor is Dr Felicity Goodyear-Smith. The first issue came out in March and contained two good letters strongly condemning the vitamin C article. You can read my letter as well as the others at www.rnzcgp.org.nz/journal-of-primary-health-care-01/

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