The digital future of infectious disease maps

•June 3, 2013 • Leave a Comment

Do Science: A back of the envelope about Claire’s killer cough

•June 2, 2013 • Leave a Comment

I’m a big fan of reason.

That’s why I don’t have a lot of time for the anti-vaxxers and the wind farm opponents etc.  It’s not always the anti-science crowd who make foolish statements though.  See my discussion on the “40% of backpain to be cured with antibiotics” and “don’t shave before a flood or you’ll die” idiocy previously.

There’s obviously been a lot of discussion about the NSW “No Jab, No Play” legislation and the advocacy journalism of the Daily Telegraph.  So this article came through my twitter feed this morning.

Selfish anti-vaccination conspiracy theorists putting Australia at risk

Even if you didn’t read the rest of it, you may have seen the leader: “My body’s a deadly weapon. So is yours.”

Later in the article is this gem:

"If I'd walked in to visit Dad with a simple case of influenza, 
let alone a more serious communicable disease, 
I could have killed the entire ward in one cough"

Ok folks…

Yes, I have this on a T-shirt

image from


  • I’m going to ignore the fact that patients in wards are usually in rooms and that only the patients in Claire’s Dad’s room would be at significant risk
  • I’m going to ignore the staff (who are probably at slightly higher risk than the patients).
  • We will assume that Claire passing through the ward counts all the patients on that ward as a “close contact”, whereas walking past a single cough would be associated with a much lower level of risk.


  • Influenza is typically thought to be droplet spread, although there is some evidence to support aerosol transmission. Droplet is generally considered to only be transmissible at short range; via directly being coughed on, or by the droplets settling on your hands when you cough and then being contact transmitted to someone else. (That’s why you should cough into your elbow not your hands).
  • The attack rate of an infection is the proportion of persons exposed to that condition that become infected.
  • I haven’t used my reference manager (Mendeley, by the way) or sourced any data except from things freely available from a Google search.

So, to the science (although it’s actually really maths)

  • Influenza attack rate: 2.4%  (reference: here via here)
  • Likely vaccination rate of hospital patients: 75% (figure for Adults >65, a reasonable surrogate, from here)
  • Vaccine efficacy: 60% (lowish average estimate, from here )
    • these last two stats mean the percentage of people with effective immunity is 60% x 75%  = 45%
  • Influenza case-fatality rate: 1% (approx rate for >65 year olds to be consistent with the vaccination rate; whole population rate is much less – of the order 0f 0.1%; data here )

So, the probability of a ward full of  “close contacts” vaccinated at current rates resulting in a death is:

Risk of exposure (strike rate) x Risk of no immunity (= 1- effective vaccine rate) x risk of death

= 0.024 x 0.55 x 0.01

= 0.0132% , or 1/7500 give or take a bit. (open disclosure: that’s a bit higher than I thought it would be when I started this)

Although, remember that I have over-estimated very significantly the risks of transmission based on a hospital ward environment, and taken low-end estimates of vaccine efficacy and a very pessimistic mortality rate.

(In case you think I’m arguing against vaccination generally, I’ll leave it as a thought experiment for you to imagine what would happen with measles, which is aerosol transmitted, and can infect people in a room 20min after a measles carrier leaves, with an attack rate of 70% ish).

The chance of lethally infecting two patients on the same ward is around one seventh that of winning first division lotto and the risks decay exponentially (note that means actually exponentially, not “really fast” as the term is commonly abused).

Why is this important and not just science pedantry?

First, because one of the reasons people want to do away with AVN is because of their long-standing practice of misquoting science to their own ends.  There are lots of people with crackpot beliefs about lots of things.  Aggressive secularists would include religion in this group. But having those beliefs is not a reason to ban organisations. Even their adherents promoting them isn’t really even good enough. It is because they are promoting them in a misleading way that AVN is in the sights (as well as their rather shoddy financial affairs and others).

If it is wrong to say “MMR causes autism” (it doesn’t), then it is equally not ok to say that a cough could kill thirty (it couldn’t). To suggest that one is bad and the other is good because of their position relative to our own biases or current public health policy is censorship, not science.

The second reason is that a standard tool of the vaccine objectors is to cry conspiracy theory.  Big Pharma, health professions and the media are in some Illuminati-backed global plot to falsely scaremonger about the risks of what *really* are benign diseases, sell vaccines and inject the public with poison.  Of course, you can never disprove this wingnuttery to a believer – because you’re part of it, man!  What I can show you is a pretty decent example of an article in the mainstream media that is falsely scaremongering about the risk of influenza (hint: I’ve hidden a link to it somewhere in this article) to people in hospitals.  Don’t feed the trolls.

Close to my own heart is the primal terror that infectious disease seems to engender in the public – from subtle influence like the difficulty I have trying to buy hand-soap that isn’t antibacterial to the very overt – all the medical students due to come to our team shortly after swine flu broke in 2009 pulled out, citing concerns over personal safety.  People think that my job poses some great risk of personal illness – in fact I’m probably at lower occupational risk than pretty much every other specialty (I don’t do procedures on people – and I know when and how to wear personal protective equipment!).


The piece in question was an opinion piece and I’m sure the feeling in question was a genuine one. But publishing nonsense in the name of science is bad for everyone, regardless of the issue or your opinions on it.  A good friend of mine is quite a fan of pointing out how poorly scientists communicate the implications of their research to the public.  But it’s really important to remember that there are two parts to “science journalism”.  Science without journalism may not get through to the public but journalism without science can misinform, mislead and create panic.

By all means, stay away from visiting at hospitals if you’re unwell.  Cough into your elbow and wash your hands.  But if you start sneezing on your way back to the car park, don’t flagellate yourself for being a “deadly weapon” – because it’s just bullshit.


Whither the progressive voter?

•May 20, 2013 • Leave a Comment

This is a great summary of the election issues facing the “progressive” voter this year.

The Opposition #NDIS no show. A rant from the heart by @R_Chirgwin

•May 18, 2013 • Leave a Comment

The epic rant of Richard Chirgwin should be preserved, especially as the media seem to have let this one go through to the keeper.

Australians For Honest Politics

Wed, May 16 2013
People’s obligation in the first instance is to be in this Parliament.  — Warren Entsch:
  1. The LNP’s absence in Parliament in the chamber for the NDIS legislation … atrocious. Nutlessness as a service.
  2. So, Abbott tells the whip “nobody attend”. Whip tells nutless sheep “nobody attend”. What a grovelling bunch of coprophages they are.
  3. A minimal gesture of respect to the disabled would have put at least Abbott in the chamber for the NDIS first reading. (Yes I’m ranting)
  4. (Mute me if you like…

View original post 1,558 more words

Professor Timestamp and the doctor

•May 15, 2013 • Leave a Comment

Before starting here, read this excellent article about NBN “analysis” from Renai LeMai over at Delimiter.

I’d had a bit of a row about this article with sortius (twitter) yesterday.  The article itself was an almost meaningless bit of fluff – someone from a pensioner’s association is pro-NBN because it will improve rural health.  There’s no specific mention of telehealth initiatives (video consulting / remote consultation etc etc) and the journalist has probably been a bit lazy in conflating the government’s eHealth website (easily found at with the clinical telehealth services (which is probably what Mr Lawler was actually talking about).

The article specifically talks about the Patient Controlled Electronic Health Record (PCEHR) – although not by name – which is the only telehealth service that is accessible from the eHealth website.  The PCEHR is designed to make it easier for people to be more mobile between healthcare providers;  hospitals, GPs can all upload data to a patients “e-medical record” and can then be accessed easily by all.  Patients are able to control which parts of these records are visible (hence patient-controlled).  It’s all done via a web-portal and is linked to Medicare’s central servers, so has access to each prescription you’ve been been dispensed at a pharmacy and each time you’ve presented your medicare card for service.  It’s not high-tech and doesn’t need any fancy equipment, other than an internet connection.

Its rollout has been far below expectations – the number of people signed up are in the thousands, three years into the 10-year project, and the number of healthcare providers is even less.

So sortius and I had been sniping at each other;  I was commenting on what was written (ie: the description of the PCEHR but no teleconsult stuff) he was commenting on what was implied.  If you’re a masochist, you can see the whole exchange here.  Such is the nature of internet flame-wars – minor differences in interpretation spiral out of control.

The argument then spun off in a different path, thanks to a tweet from @stryqx.

Reproduced below:


So we were arguing at cross purposes the first time around, but here are two tweets specifically talking about the health record, which sortius quite clearly says [people aren’t accessing the PCEHR] probably because they don’t have a stable internet connection.

He then proceeds to have his little meltdown about me verballing him.  He then straw-mans the rest of eHealth from our previous argument as justification for me being incorrect and then when I quote his words back to him (remember, the ones I verballed him with) he says “Firstly, I said probably”.  Ahh, of course.  The irony, of course is that he wrote an excellent postyesterday – about people complaining that the internet records things you say and can be checked on.

I’m happy to concede his point that people with poor connections are less likely to take up internet technology.  Fair enough, but the PCEHR is not all of eHealth and to bollock me for saying that (when I didn’t) while denying he said something (that he did) is just infuriating.

What really annoys me about sortius’ approach to this is his argument (also in his comments to my previous post here) is that if you know tele- but not -health you should be taken seriously, but if you know -health but not tele- then you are an “uneducated fuckwit”.

And of course that he complains frequently that Malcolm Turnbull has blocked him for being an “anonymous troll”, but that after a spray of vitriol, he blocks me on twitter.

Recognising hypocrisy in yourself takes self-awareness.  We can only hope.

(cheers to Geordie Guy for the title)

Journal Club: Antibiotics for back pain

•May 9, 2013 • 4 Comments

This is a bit of a departure for me, but this article has been getting a lot of attention in the media, so I think it’s worthwhile doing. First, a disclaimer. No blog or any other page on the internet is a substitute for proper medical advice you get from sitting down and talking to your doctor. Every situation is different – and I think that particularly for this paper, as it deals with a chronic condition, the best person to speak to is the one who knows you best. The abstract for the article is available here and the full version is here (will need to login to your hospital / university website to get the full version). Some of the sensationalist media it’s received is here or here. ABC Radio did a piece, and a more skeptical report is here.  Michael Vagg has covered the article over at The Conversation and must be a clever guy because he largely agrees with what I’ve got to say below.

Short summary

A randomised, placebo controlled trial of amoxicillin/clavulanate given for 100 days to people with chronic lower back pain has showed a statistically significant reduction in pain, functional assessment and MRI changes.


Chronic back pain is a common cause of presentation to GPs and accounts for quite a bit of lost working time. By and large, existing treatments are not highly effective, and mainly involve rest early and then gentle mobility with pain relief.  There, unfortunately, is no magic bullet – no matter what people say. Chiropractic is about as effective as standard care – which is to say not very. In clinical studies, most patients with non-specific lower back pain, it will resolve spontaneously – this tends to occur in spite of treatment rather than because of it. Unfortunately, a small proportion of patients will go on to have severe, ongoing symptoms. There is concern in medical circles about the steadily increasing prescription of strong opioid pain killers – morphine, oxycodone tablets and fentanyl / buprenorphine patches. The Australian therapeutic guidelines recommend against chronic use of these agents. The other treatment option is surgery – although for most cases where there is not a substantial anatomical defect, the results are also less than inspiring. Another problem is that surgery is frequently done late in chronic back pain  – after everything else has been tried, and a chronic pain state has been established and which surgery may not fix.

Rationale for the trial

For most patients with back pain without any of the warning signs, no scans or x-rays are generally needed. If an MRI is done, changes called “Modic changes” are commonly seen. These can be thought of as inflammatory changes in the edges of the vertebrae.  I’m not an orthopaedic surgeon, but I am reliably informed that these modic changes are an important predictor of pain – which makes sense.  Inflamed bones are painful. The next leap is where I have the first big problem with the article. Not all inflammation is due to infection.  I hope this is pretty obvious.  Think of a sprained ankle;  it gets really swollen, but there’s no suspicion that it’s infected.  So it is (I think) with these modic changes.   The paper’s rationale for using antibiotics is based on a previous work of Sterling and colleagues (doi:10.1016/S0140-6736(00)05109-6) and quote it thus “Stirling found nuclear tissue removed under strict sterile conditions to be infected with low virulent anaerobic organisms, (Propionibacterium acnes and Corynebacterium propinquum) in 53% of patients.  It’s also worth noting that the samples were incubated for a long time in the lab (increasing the risk of contamination by the lab staff) and that this was tissue taken from the intravertebral discs (not the bone end-plates) of people with sciatica and bulging discs (not functional lower back pain).

Now Propionibacterium is a tricky germ to grow – slow growing, and grows better under conditions without oxygen – which is fiddly in the lab.  As well as being the germ behind acne, it is also prone to cause infections in shoulder reconstructions.  Those aside, the vast majority of times we isolate this germ in the lab, we think of it as a contaminant rather than a true infection. It is a ubiquitous organism on the skin, and if not enough care is taken collecting samples, it is very easy to contaminate a sterile specimen with a small amount of this germ.  Obviously in response to the Stirling letter, was the paper of Carricajo et al (doi:10.1016/j.jhin.2007.04.007) which found that only 2 of 54 patients with herniated discs cultured P. acnes, and that both these patients also cultured the organism from the ligamentum flavum and paraspinal muscles.  As well as that, 18 other patients also cultured the organism from the control sites but not the disc, and four air samples from the operating theatre were also positive for P. acnes.    Their conclusion was that contamination was a far more likely explanation than a low-grade infection.

Statistical Power

The trial was small – around 70 patients in each group, but the sample size was calculated to find a difference in the grading scores, with a power of 0.90 – the short version of this is that there’s a 1/10 chance of a Type II error – that is finding a difference where none exists – purely by chance.   You would think that such a large magnitude of difference would make a statistical fluke less likely, but in fact a small sample size could result in a cluster of aberrant results away from the true answer more easily than a larger trial.

Adverse Effects

The adverse effects in this trial were significant (all antibiotic vs placebo):

  • Any adverse effects:  65% vs 23%  (mainly loose bowel motions / flatulence)
  • “Middle grade” effects:  27% vs 11% (defined as lasting > 3 weeks)
  • “Considerable” effects:  21% vs 6%  (not defined at all)

What wasn’t considered was secondary effects of the antibiotics – creation of resistant organisms in the patients which may not come up during the duration of follow-up of the trial, and the wider effects of antibiotic resistance on the community.


A well-designed, but small trial has shown marked improvement in outcomes of a condition for which, up until now, treatments have been largely unsatisfactory.  Although there is biologic plausibility, the causal link is weak, and there has been another small study which specifically calls into question the whole premise that underpins the trial.  The treatment is cheap, and certainly a better option than putting people on chronic opioids, but has significant side effects – and further population-level side effects which the trial does not look into (and which are generally poorly appreciated by everyone – public and doctors).

Far from being the potential Nobel prize winner that it’s been reported as, I think this trial – overall – is a bit of a lemon.   I’d like to see a much larger trial, which also includes some data on rates of trial-acquired resistance.  But it is an important first step – and as the cliche goes, more research is definitely needed.


Antibiotic Resistance on ANZAC Day

•April 25, 2013 • Leave a Comment

There’s not much that will stop me from banging on about antimicrobial resistance.  Preventing it is my job – and my passion – I’m lucky enough to have landed a job doing something that really fits with what I like doing.

NPS Medicinewise (formerly the National Prescribing Service) do a lot of great stuff in promoting appropriate use of medicines (not just antibiotics) and their page on antimicrobial resistance is a great starting point if you want to read about the topic.  They also co-ordinate a national hospital antibiotic use survey in September (which is the source for a lot of my stats on antibiotic use) and have some great educational resources for prescribers (if you’re a junior doctor reading this:  do these modules).


This tweet popped up in my twitter stream this morning, linking to this video.

I love the video – I think it’s great to hear from people who can see the enormous difference that antibiotics have made in their lifetime – because otherwise, it’s just doom-sayers like me predicting a return to the time when we don’t have effective antimicrobials.

But I’m just not sure how comfortable I am about leveraging ANZAC day for a public health message.

There’s quite a bit of navel-gazing this year about ANZAC day – as people become more remote from the diggers it all started with.  See the excellent thoughts of John Birmingham here.  Whether or not that’s the case, I suspect the outrage engine would be in full-swing if a business ran ads trading on the ANZAC story.  I’m just not sure we should treat a public service message any differently.

In any event, ANZAC day is important and although its meaning to the general public may shift, I think we should keep its observation low key (in fact, I quite like Jon Kudelka‘s suggestion.

Antibiotic resistance is also important.  But let’s get rid of the overlap between the two.

But really – watch the NPS video anyway.


Telehealth Gloves are Off Again

•April 5, 2013 • Leave a Comment

Hat tip to Geordie Guy for alerting me to Nick Ross’ latest foray into Telehealth.  I hadn’t heard it myself, of course, because Nick has blocked me on Twitter following my last rant.  In the fallout from said rant, I also contributed to a discussion on Whirlpool about Nick’s massive article.

Another good article in the interim on the NBN and telehealth is the article by Kath Crosby (twitter) on Ausvotes2013.

Nick’s comment on my last post implies that he’s interacted with me regarding my concerns, and he said as much again in the whirlpool thread.  I posted a rebuttal of this, as well as a reply to the people in that thread who felt my mind was closed to Nick’s truth (fair acknowledgement to Nick for saying he wants to change my mind with facts – about bloody time!)  but the mods considered it off-topic, so here it is again.

Nick has not interacted with me in any significant way following any of my posts.  Specifically, he has not cited any new evidence at all apart from the articles he linked to in his telehealth articles (all of which I have linked to from this blog).

I made the point that Nick’s crowdsourcing of articles from whirlpool has already turned up a larger number of better-quality articles than Nick had posted on ABC T&G to date… which makes me rather wonder what actual evidence he was basing his previous assertions on.

And finally, I’ll be delighted if his request turns up enough good quality articles to support his opinions.  If it does, then I promise I’ll be the first to change my tune.

I would, however, still really like Nick (or someone else of his choosing) to address the same questions that I’ve repeatedly asked here (and elsewhere).

And finally, I’ve trawled twitter and my gmail and have screencaps that show Nick’s entire interaction with me on this issue;  which consists of him repeating his opinions and what is clearly the best justification in the history of rhetoric – “I don’t write things which can be proven wrong”.

Well.  Glad that’s settled then.


Nick Ross does it again

•February 23, 2013 • 14 Comments

See my previous posts on this subject here, here and here.

First, my standard disclaimer:  I am in favour of the NBN and rather despair that Malcolm Turnbull – who really should know better continues to promote what he must know to be an inferior policy for either party-political or purely budgetary reasons.  Lots of Australian tech journalists continue to hold him to account for it – notably Renai LeMay at Delimiter (twitter) and Nick Ross from ABC Tech and Games. Nick and Malcolm had a bit of an exchange at the kickstarter conference recently.

Nick’s latest effort is a massive opus on why he continues to support the ALPs broadband policy over the LNPs.  This certainly isn’t surprising, given the digital column miles Nick has put in previously.  He’s certainly committed to the cause.

In addition to sending Nick links to my blog posts on telehealth, I have messaged him my email address and offered to discuss with him why I think his assertions on telehealth are incorrect.  I’ve had no response to this offer and his replies to my blog posts have consisted of telling me that I’m wrong (with no evidence to back it up) that he “doesn’t post things that are incorrect” and a request for me to lay off because he thought that my nitpicking was damaging the pro-NBN stance we both have.  I have forwarded him some Queensland media links – which he has been happy to use in the article, I note, but has not at any time addressed my long-form criticisms of his telehealth misinformation.  I’m very disappointed that most of the too-ing and fro-ing about these articles take party political lines – people accuse Nick of anti-LNP bias while people arguing the case are accused of being LNP hack.  The comments on Nick’s article and this response demonstrate this clearly.

Well, Nick, I am calling you on your bullshit one last time.

  1.  As Malcolm (and I) have pointed out, many centres are using current broadband for telehealth (including Queensland Health) and the bandwidth is adequate for medical consultations.  Provide evidence on how NBN will improve this
  2. Please provide any sort of costed document to support the fact your ridiculous (and as yet, repeated without even a single link to support the savings) assertion that savings in health will fund the NBN by themselves
  3. Please explain how your assertions about ambulance transfers, in-house monitoring, and diagnosis and triage are more correct than my disputations of them here.
  4. Please explain to me having a kinect sensor monitoring someone for a fall delays admission to a nursing home.
  5. A significant proportion of your links are to firms selling telehealth services.  Do you think these people are likely to be giving you unbiased advice?   Can you comment on how you think it would be accepted if I, as a doctor, was to say to a patient “I am going to put you on a drug because the drug company representative promoting it tells me it is the best drug ever”

And finally – and I cannot begin to explain to you how glad I am you did –  included this in your article:

Another class of patient that would benefit from telehealth is those whose immune systems are suppressed, either by disease (AIDS is only the most famous, not the only immune-suppressing disorder) or by treatment either with steroids or a large number of chemotherapy drugs. Wherever possible, such patients need to avoid hospital, both for their benefit and so they don’t become “Typhoid Mary” carriers of resistant bacteria to others.

The potential cost savings from not having to touch infectious patients are also substantial.

This is unmitigated bullshit of the highest order and demonstrates to me more clearly than ever that you do not have the faintest idea about what healthcare actually involves.  Fortuitously, it also exactly falls within my area of specialisation and I therefore look forward to you either: a) admitting that you are wrong; b) asserting that I am wrong and displaying your arrogance or c) actually trying to engage people who have relevant expertise in the debate.

You are correct that there are many diseases which result in immunosuppression.  There are around 25,000 people in Australia living with HIV (2Mb PDF), only about 1/6 of whom have advanced disease and would be considered immunosupressed.  Patients who are receiving immunosuppressant therapy do need regular review (and frequently blood tests as well) – usually in outpatients.   This is certainly an area where good telehealth could make a difference; although again, this is being done with existing telehealth technologies.  The patient will actually need to see a healthcare professional to have the blood tests, however;  there are advances in microarrays that can be “bloodtests on a chip” but these are many years away from being in the home and plugged into a free USB socket.

That leaves patients with severe immunosuppression;  for example in induction chemotherapy for leukaemia.  Depending on the chemotherapy used, these patients can have no infection-fighting white blood cells for weeks.  They are at risk of rapidly developing life-threatening infection.  Some low(-er)-risk ones may be managed as outpatients with antibiotics.  The rest require admission for observation – as they may rapidly develop sepsis – where the greatest determinant of survival is time to receipt of antibiotics -which will always be longer if patients are at home.  This downside of being at home overwhelmingly outweighs any theoretical (ie: has never been proven) benefit that may come from them staying out of hospitals.

Your link relating to “not having to touch infectious patients” is to a commercial site that does not provide any evidence to back up your assertion.

What costs are these?  Handwashing?  Healthcare staff should be doing that anyway, and has been consistently shown to be one of the most cost-effective interventions at preventing infection.  Gloves?  Similarly, these are part of the WHO-recommended standard precautions.  Physical examination contributes to the making of an accurate diagnosis, so what about increased costs of investigations and imaging that would (more than) offset cost-saving from whichever of these things you actually meant?

So, Nick…

You incessantly lambast Malcolm Turnbull for not espousing an evidence-based policy, but you cherry-pick studies that support your own pre-existing theories, link to commercial providers who are selling telehealth products as if they are impartial third-parties and continue to make unsupported assertions that I (and others) have been directly challenging since August last year.  You provide no actual figures to support your cost savings and have never directly addressed specific queries on from where you arrive at your assertions.

I don’t give a toss about allegations of ABC bias, but your articles are clearly more opinion and wishes than facts.  Stating your feelpinions over and over and over again, louder and louder and in longer and longer articles does not make them true.  Refusing to admit there might be any other points of view make you look like your mind is very firmly closed (which I think it is), but bollocking Malcolm for the same thing while doing it yourself makes you look like an outrageous hypocrite.

Put up your evidence, engage with people who disagree with you rather than going off at them, or just STFU.

Follicular Flood Furphies

•January 29, 2013 • 2 Comments

Brisbane is flooded again, although thankfully not as badly as in 2011.  It is always worth a shout-out to the awesome work our emergency services to – particularly the volunteers in the State Emergency Service who get out and about to help out while the disasters are ongoing and without any payment or reward.

I had a brief exchange with one Brisbane volunteer here over the weekend and again today, in response to a similar tweet coming from St John’s Qld.  After a quick bit of Googling and some Pubmed, my assessment is here and here – there is no direct evidence or guidelines (that I have been able to find) that recommend this.

So where has this helpful advice come from?  And why is someone who’s job is preventing infection having a cranky about it?

Well, like many of these things, there is a seed of truth at the bottom of it all.  In preventing surgical site infections, there are actually really quite a few studies (including a Cochrane review) of the impact of methods of hair removal on the risk of getting a surgical site infection if you’re having an operation.   The bottom-line:   we don’t really know, because the studies are small, the events are rare.  The data is underpowered to find a difference between no hair removal and hair removal, but what they do say is that if you shave, your risk of infection is around twice that if you clip (relative risk: 2.09, 95% CI: 1.15-3.80).  It is now standard surgical practice for hair to be clipped, not shaved.

Why this might increase your risk of surgical infection is unclear;  microtrauma to the skin is a popular theory, but there are others – opening the pores to allow bacteria normally on the skin surface to gain entry into the hair follicles is another.  The thing you have to remember is that surgery is a major insult to your skin.  (After lathering it with antiseptic) it is cut, stretched, sometimes burnt and then stitched.  It creates a cold, poorly blood-supplied bit of tissue that is open to the outside world into which the residual bacteria (which residual bacteria?  These ones. Surgical prep is better than hand sanitizer, but your skin is not sterile) fall and can set up a wound infection.

This is not your leg in a gumboot full of Brisbane river water.

What we do know is that healthcare staff do see an increase in the number of skin and soft-tissue infections in the period immediately post flood.  We certainly did in Brisbane in 2011.  There is also a small increase in the number of unusual infections (things like Aeromonas – which likes living in fresh water but is normally a very rare cause of wound infections) but the vast majority of these are caused by Staphylococcus and Streptococcus – which are germs that are living on your skin right now.

Why do we see these infections after floods?   I’d guess that there is a combination of factors, including cuts and abrasions from submerged debris. In the Queensland summer, I reckon tinea pedis is a major player – one of our tricks of the trade in infectious diseases is to cure a person with recurrent bacterial leg infections by looking between their toes and treating their tinea – causing splits which let the bacteria in – which no other doctor has thought to look for.   The other infection that people have mentioned is “that foot spa thing” – you’re probably thinking of Mycobacterium fortuitum  – which lives in fresh water and likes warm places – and isn’t killed by whatever that awful radioactive blue antiseptic they put in those foot spas.  It’s not much of an issue in floods, but the hair pulling and then soaking your feet in a warm pool of contaminated water is a risk for infection.  (Disclaimer for foot spa attendees:  it’s quite rare, so don’t stress).

So perhaps shaving your legs could have a minor impact on the risk of infection, and surely if we can do anything to prevent infection we should?  Well, I don’t think it’s always the case.

I think that emphasising the wrong message is harmful.  People (unfortunately) have limited capacity to remember public health messages.  I think it’s far more important to emphasise the importance of hand washing after grubbing around in the mud than to focus on the shaving message.  It’s a much more bang-for-your-buck intervention.

In a way, it’s like telling tourists to North Queensland that they should watch out for red-backs under the toilet seat rather than not swimming where crocodiles or irukanji might be lurking – or for that matter, not encouraging them to cover up from the sun.

Most of these skin and soft tissue infections will be mild and self-limiting.
The important messages are to:

  • keep any wounds you do have covered up
  • wash your hands
  • if you do develop an infection, see your doctor
  • mention that you’ve been working in the floods

and don’t stress out if you’ve shaved your legs.  It’s probably not going to make that much difference.  Even less so for your face or armpits.  The Queensland Health public health communique that will be sent to doctors statewide shortly doesn’t mention a damn thing about shaving, and neither does any flood-response guideline I’ve been able to find on the internet, so stop putting the fear of pestilence into shavers everywhere.

But wash your hands!