Spider attack or a web of lies?

One of the more common types of public enquiry I get as a natural history curator is about spiders. Every year in September people start reporting large spiders that they don’t recognise and which therefore *must* be invasive species or tropical escapees from packets of bananas. Every year I either reassure (or disappoint) those people by explaining that the spider they have discovered is a common species in its fully-grown adult stage, sometimes looking a bit on the bloated side because it’s full of eggs.

Araneus_diadematus_comparison

Garden Spider (Araneus diadematus) full of eggs. Inset: comparison against non-gravid Garden Spider abdomen – note the characteristic cross pattern.

This year has been a bit more active on the spider enquiry front, because there has been a lot of scaremongering about spiders in the tabloid press. Beyond the usual September influx of sightings when adult male spiders become more active as they seek females to mate with, there has also been an increase in the number of requests for identification throughout the year, with people unnecessarily concerned about the Noble False Widow (Steatoda nobilis) spreading steadily northward as the global climate warms.

Male Giant House Spider (Eratigena atrica) on the lookout for females. Inset: note the 'boxing glove' pedipalps that show this is a male

Male Giant House Spider (Eratigena atrica) on the lookout for females. Inset: note the ‘boxing glove’ shaped pedipalps that show that this is a male

With all this frenetic arachnological activity I thought it might be time to lay to rest some common misconceptions about spider bites and offer a reality check to counter some of the over-hyped reports of injuries blamed on spiders.

Spider bites

Spiders in Britain are pretty harmless critters. So far there have not been any reported deaths in the UK from spider bites ever. You are literally more likely to be killed by being struck by lightning.

This is partly because spiders very rarely bite people, despite what you might be told by the press. The UK is full of things that do bite however, such as mosquitoes, midges, horseflies, ticks, bed bugs and fleas. All of these unpleasant beasties have a reason for biting – they are after your blood. Spiders are not. They will generally only bite when they feel very threatened.

Another reason why spiders in the UK are not life-threatening is simply that their venom doesn’t pack enough punch. The most venomous spider living in the UK is the Noble False Widow, which can give a painful bite, similar in intensity to the sting of the Common Wasp (Vespula vulgaris).

NobleFalseWidow

Noble False Widow spider – a little visitor in my kitchen

Keep in mind that a Common Wasp is far more likely to sting you than a Noble False Widow is to bite you, since the spiders are not aggressive – they largely keep to themselves and they don’t try to mug you for whatever sugary food or drink you have available.

A few other spiders in the UK can also bite, sometimes painfully, but again their venom is meant for subduing small invertebrates rather than humans, so although you may get some pain and perhaps swelling some time after being bitten, that may persist for a few days, it shouldn’t cause you any serious problems unless it gets infected.

Spider bite or MRSA?

Now this is where it gets interesting. Cellulitis caused by bacteria like Staphylococcus aureus (or ‘staph’ for short) can commonly be mistaken for spider bites. Any bites, stings, scrapes, cuts or even hair follicles in the skin can open the underlying tissue to infection, leading to necrosis of the skin, similar to that caused by the bite of certain spider species – in particular the Brown Recluse (Loxosceles reclusa), which it’s worth noting does not occur in the UK.

Cellulitis - not a spider bite! Image by James Heilman, MD

Cellulitis – not a spider bite. Image by James Heilman, MD

In areas of the USA where the Brown Recluse is also not present, it still gets blamed for a large number of injuries that are actually caused by staph bacteria that are resistant to Methicillin antibiotics (this is the strain of bacterium more commonly known as MRSA). In one study assessing the possibility that MRSA had become established in a prison community, half of the study group incorrectly assumed that the symptoms of their MRSA infection were symptoms of having been bitten by a spider.

In fact, it seems that spiders regularly get blamed for injuries that they don’t cause. One American study reported 216 medical diagnoses of Recluse bites in Western states in 41 months, despite the fact that the spiders don’t naturally occur in those areas. In fact there had only ever been 35 confirmed sightings of Recluse spiders in the regions studied, which really doesn’t add up: how can non-existent spiders be biting people?

Why blame spiders?

It seems that there are a few factors at play here, not least irrational arachnophobia fuelled by irresponsible reporting in the press. People are told about ‘deadly’ spiders and then when they get an infection they assume that it’s actually a reaction to a spider bite. They then tell the media they’ve been bitten by a spider and the vicious circle is complete.

People also assume that a bite has been caused by a spider because they have seen a spider nearby. However, that spider is probably an innocent bystander that’s more interested in eating the bloodsucking pest that actually caused the bite – assuming that it’s a bite at all and not cellulitis caused by something else.

Cellar Spider (Pholcus phalangioides) feeding on a different spider species

A Cellar Spider (Pholcus phalangioides) intent on feeding on a another spider species and not remotely interested in biting humans

Finally, the effects of spider venoms are often very poorly understood, because they are so frequently conflated with a variety of other dermatological problems and the rarity of confirmed bites means that little research has ever been carried out. That means medical staff are operating from a poor information base and may rely on poor information when making a diagnosis. The danger here is that significant medical issues (such as the spread of MRSA) may be overlooked because spiders are being unfairly blamed.

So if you read a case in the media about some horrible ‘spider bite’ it’s sensible to remain a bit sceptical. If the spider wasn’t seen actually doing the biting, the chances are the injury wasn’t actually caused by a spider at all. More likely it’s an infected wound, maybe following a bite or sting from something else with a taste for human blood or the sweet things we eat ourselves.

UK homeopathy awareness week

June 14th – 21st 2010 [and 2012] is the UK homeopathy awareness week, so I thought it might be a good idea to try and raise awareness of homeopathy.

Cinchona

Homeopathy is based on the principle of similia similibus curantur (likes are cured by likes). The hypothesis is that symptoms of illness are caused by a derangement of the ‘vital force‘ assumed to be present in a living organism and substances which elicit the same derangement (i.e. symptoms) will rid the body of the illness. This was originally identified in the context of homeopathy by Hahnemann with reference to cinchona bark (source of quinine) and malaria. The previous proposed mechanism of effectiveness of quinine against malaria was its bitterness, but Hahnemann sensibly identified that other bitter substances did not offer the same protection. Instead, after taking cinchona and experiencing a reaction similar to the reaction he associated with malaria, he hypothesised that it was this similarity in symptoms that made cinchona bark effective.

Modern homeopaths still use a similar method to identify their treatments. When in a healthy state they try a preparation and keep a detailed diary of any effects that they feel the treatment has on them. This is called ‘proving’ although what it is supposed to prove is hard to determine since there are no rigorous controls in place and the results are not statistically tested to see if they are anything other than random. Consider the perceived effects of taking peregrine falcon blood for example:

Short statement on peregrine falcons:

The Peregrine Falcon is widely renowned for its incredible speed. Estimates vary, but commonly cited top velocities are in the range of 290-320 km/h (180-200 mph), achieved only during the characteristic swoop (hunting dive)…the Peregrine Falcon is the fastest creature on earth.

Observation during proving:

‘Drove back from the party (had some wine but not so much) quite fast but well, changing speed as necessary. It seemed faster to the others in the car than to me.’

I heartily recommend reading the entire page about the proving of peregrine falcon blood – it is an education into how homeopaths derive their information about the treatments they prescribe (and it is ludicrous to the point of hilarity). Is this really a rigorous approach to testing healthcare products or is this more about symbolism, appeal to the mystical and delusion?

Evidence based medicine occasionally does use elements of  similia similbus curantur such as with inoculation and vaccination – where a small or denatured dose of a disease causing agent is introduced with the intent of stimulating an autoimmune response that will prevent the full blown disease from becoming established should the person come into contact with a large active dose of the pathogen.

Foxglove

Also, many physiologically active compounds have medicinal uses because they act on particular organs and metabolic pathways via a biochemical route that can have apparent similarities to the illness being treated. For example, digoxin is a cardiac glycoside found in foxgloves that decreases heart rate and increases force of heart contraction – fatal in large doses, but useful for treating atrial fibrillation in small doses – so at a very gross level this could be considered ‘like treating (rather than curing) like’. It is also vaguely plausible that a substance which elicits a physiological response which mimics symptoms of an illness that arise as part of the body’s  immune response (such as raising temperature) may have the effect of fighting an infection (although I have not seen any evidence for this).

Hahnemann’s experience with cinchona happened in 1790 when the medical community of the time was still dominated by the miasma theory and humourism of the Middle Ages. Vitalism was a standard of the medical profession at the time, with good health being dependent on balancing the four vital humours. The idea of a biochemical autoimmune system did not take shape until a century later, but when it did it revolutionised the medical field, bringing about treatments with previously unprecedented success (eradication of smallpox anyone?). Hahnemann had no idea about the mechanism by which the body actually heals itself, he also had no idea that malaria was not caused by a miasma, but by a microscopic parasitic protist of the genus Plasmodium.

Plasmodium falciparum – the protozoan that causes malaria

In short Hahnemann was trying to fit his limited observations into a theoretical framework consistent with the body of assumed knowledge available at the time. The same way that scientists have always worked. However, over time the body of knowledge has changed – vitalism has been rejected as evidence has been amassed which demonstrates that all of the functions historically proposed for vital energy are demonstrably biochemical in nature. Disease is now well recognised as being caused by bacteria, viruses, proteins and biochemical abnormalities rather than by derangement of ‘vital energy’. The idea of a vitalistic treatment for a biochemical problem seems rather at odds with the facts, particularly since there is no evidence to suggest that vital energy even exists. Sticking with malaria, we now know that the antimalarial component of cinchona is quinine, which is no longer effective as an antimalarial due to the resistance evolved by Plasmodium – how such immunity might have evolved in response to vital energy is hard to fathom.

Homeopathy also subscribes to the principle that the smaller the dose, the more effective it is at influencing the vital energy – to the point where homeopathic remedies are diluted until they no longer contain even one molecule of their active ingredient. Indeed it would take a ball of water the size of the solar system to contain one molecule of active ingredient in the more ‘potent’ homeopathic remedies – making them even less tangible than the Emperor’s new clothes. Of course this idea of smaller doses having a bigger effect flies in the face of everything that is demonstrated in evidence based medicine, where dose dependent effects increase with increasing dose size, through a therapeutic window until a plateau is reached or there is an overdose.  The Ten23 campaign was all about this misplaced faith in super-dilution.

If homeopaths were able to demonstrate that vital energy exists then homeopathy might have a theoretical leg to stand on, as would chiropractic and a suite of Ayruvedic medicines, but without any evidence for vital energy they remain theoretically unfounded. Interestingly, mainstream medicine was once based on the concept of vital energy, which has only been discarded due to improvements in experimental methods. Vital energy is one of those strange forces in nature that becomes harder to see the harder you look for it – probably because it only exists as a cultural concept that has no relevance in the physical world. This erosion of evidence for vital energy not only leaves homeopathic theory unfounded, but necessarily rejected.

Headstone for 9 month-old girl who died because her parents chose homeopathy over conventional treatments

Theory aside, if there was strong evidence for efficacy of homeopathic remedies then there would be very good reason to question the laws of physics and our current understanding of biology and medicine. However, there is no persuasive evidence for homeopathy’s efficacy. As such it seems bizarre that people still hold on to this outdated and superseded faith-based system of medicine; but then again there are still Flat EarthersFaith healers and people who drink their own pee, so I suppose it’s no great surprise. There are dangers however – if people choose to use homeopathy in place of medicines that have evidence of efficacy, they run the risk of harm or even death – and I think that’s something everyone should be aware of.

One lump or two?

One lump or two? 'High potency' homeopathic pillules are nothing but sugar

The 10:23 campaign seems to be stirring up a wasps nest amongst homeopaths – fortunately these wasps have a venom so dilute that they are incapable of doing much more than make an angry buzz. I would feel sorry for them if they weren’t so adamant that their flimsy belief system is capable of treating serious illnesses like type I diabetes, gangrene, appendicitis, AIDS, malaria, etc. (you don’t believe that they make such claims? check out Nancy Malik’s twitter account: http://twitter.com/DrNancyMalik).

Of course, some homeopaths have taken up the #ten23 hashtag and are fighting a spirited (and sometimes spiritual) battle against the arrayed forces of science, scepticism and general doubt (as is their right). Needless to say their response does tend to rely heavily on bombast, unfounded statements from anecdote and links to videodotes or webpages promoting homeopathy, although seldom to anything resembling rigorous, peer-reviewed scientific studies (the odd basket of carefully picked cherries does turn up). But of course, science is clearly lagging behind – in the words of one homeopath twitterer (@HomHeals):

Homeopathy – Waiting for Science to Catch Up!

This made me chuckle, because it put me in mind of other unfounded beliefs that science has caught up with and subsequently shredded with Ockham’s Razor – like Jack the Ripper in a lab coat.

Approximation of my mental image of science armed with Ockham's Razor, hunting down woo. DISCLAIMER This is in no way meant to represent a threat of physical violence - I abhor such things.

Scary science is gonna get you! DISCLAIMER This is in no way meant to represent a threat of physical violence

But of course, it’s not like that. There is no dichotomy between science and homeopathy. Science is a process whereby evidence is assessed in a systematic, repeatable way and ideas are accepted or rejected on the basis of the outcome, whilst homeopathy is a set of beliefs based on a defining principles established by Samuel Hahnemann 200 year ago. These principles as a set have simply failed to stand up to scientific testing, so homeopathy finds no support from science. This means that for homeopaths to continue doing their thing, they need to reject the principles of the scientific method (i.e. reliance on evidence), rather than change their ideas about homeopathy. In response to the rhetorical question posed by John Maynard Keynes:

When the facts change, I change my mind. What do you do, sir?

A homeopath would probably respond by saying:

“I ignore the facts – they’re not my facts anyway, they’re facts made up by people who are colluding to besmirch the name of homeopathy and I have anecdotal evidence that is far more convincing than your double-blind, randomised, placebo controlled trial anyway. And your facts are just made up by big pharma, which doesn’t work and it kills people. You’re just a bunch of allopaths who don’t recognise the true faith of homeopathy. So there.”

What is particularly vexing about debate with homeopaths is their inevitable retreat into logical fallacies and long outdated arguments. They make statements about homeopathy being better than allopathy, when allopathy was a phrase coined by Hahnemann 200 years ago for the Hippocratic, Galenic etc. schools of medicine, long since made defunct by Germ Theory in the 1880s and the rise of modern evidence-based medicine, which has been around for less than 40 years.

In effect, modern medicine has successfully overhauled the established medical opinion of Hahnemann’s time by virtue of being more effective. If homeopathy was as effective as homeopaths make out, it’s surprising that it isn’t the method that has been adopted as the best form of treatment available – after all it has been around longer and it’s cheaper to produce because it doesn’t require all that pesky testing. Moreover, it sells in huge amounts – but popularity is not a robust indicator of efficacy by any means, as I’m sure any homeopath could tell you… if they weren’t so obsessed with popularity.

Before this post turns into a huge rant or a serial refutation of the nonsensical arguments used by homeopaths, I will try to make my point. 10:23 is about what is in a ‘high potency’ homeopathic preparation (of 30C or more). These products are marked as having active ingredients, but the dilution of whatever ingredients might have been in the solution at the outset is so great as to go far beyond the Avogadro constant – in short there is less than a single molecule weight of the ingredient in the solution. This solution is then dropped on sugar and allowed to evaporate. So should it be marked as being an active ingredient? It’s rather like a bag of sugar listing Tyrannosaurus rex as one of its ingredients, because there is a possibility that one molecule of water that dried on one grain of sugar was once in contact with a T. rex (see here for a clear summary of the homeopathic process).

Despite the lack of any robust support for efficacy of super-high concentration homeopathic products, the UK’s leading high street pharmacist, Boots, sells these products with the full knowledge that they are not shown to work:

I have no evidence before me to suggest that they are efficacious, and we look very much for the evidence to support that…

(Paul Bennett, Professional Standards Director of Boots speaking at the Science & Technology Committee Homeopathy inquiry 25th Nov 2009 – full transcript here)

This seems wrong. It seems as though a trusted company is betraying people’s trust – falling back on caveat emptor (let the buyer beware) rather than maintaining the standards of what they sell. Imagine if Boots started selling travel sickness pills that contained no active ingredient, just sugar. This would be a placebo and it would be unethical (and probably illegal) for Boots to sell the product. Which may explain why Boots don’t indicate what the homeopathic pillules they sell are for. In effect, they do sell travel sickness pills that contain no active ingredient, just sugar (it’s called Aconite 30C) but they get around the ethical and legal problems using the disclaimer:

Boots Aconite 30c is a homeopathic medicinal product without approved therapeautic indications.

Contains ingredients:

Active Ingredients: 30c Aconitum napellus

Also contains: Sucrose & lactose

(taken from Boots website)

It would be interesting to see if the listed ingredients would actually stand up in a court of law, given the lack of any molecules of Aconitum napellus in the product – it’s rather like an apple pie with no apple.

The 10:23 campaign is intended to make this point in the public eye, to raise awareness of what super high dilution homeopathic pillules actually consist of – nothing but sugar. That’s why I will be taking part in the London leg of the homeopathic overdose at 10:23 this Saturday. Perhaps it will make the point publicly enough to persuade Boots that they shouldn’t be misleading the public by stocking homepathic remedies that are not shown to work and are listed as having active ingredients, yet they contain nothing but sugar.

“One lump or two?” Not for me thanks – I’m cutting down on woo.

WTF is homeopathy?

My first exposure to the word ‘Homœopathic’ was at Hampton House, a hall of residence at Bristol University which was an ex-homœopathic hospital (and is now the student medical centre). All I knew was that it was a magnificent building that used to be a hospital of some sort – but I never really thought about what the ‘Homœopathic’ bit meant – I just assumed it was another branch of medicine. Continue reading

Failings of ‘parental intuition’

I am concerned by all the irresponsible, selfish and stupid parents of the world. The ones that upon reading this would be moved to comment along the lines of “you’re not a parent, so you don’t know anything” – because that is how arrogant and self-righteous the sort of parents I am thinking of are.

parenting

Being a parent does not make you immune from criticism, it does not make you an expert in rearing children and it does not make you medically qualified, intelligent or well informed. It may, however,  make some people more selfish, overly-defensive and irrational. Not only do some parents think that society owes them for having children (I for one didn’t ask them to have unprotected sex), but they also seem to think that their ‘little darlings’ are beyond reproach and any trouble that they get into is somebody else’s fault. Continue reading

Mail online – ‘Homeopathy works!’ Part II

Right (rolls up sleeves), I said I would try to track down the reference that the Mail Online used in their comment adverse and misleading article by Jenny Hope, so that I could comment further. It has been tracked down – not by me I am ashamed to admit, but by EoR who commented on a blog about the same article at Thinking is Real.

Here it is in all its glory in the BMJ ( 19 August 2000) pp. 321:471-476 . Notice the date? It’s nine years old, which explains why I couldn’t find it – after all, it was supposed to be news, so I foolishly expected it to be new. Silly me. Continue reading