Thursday, 29 September 2016

The Internet Has Ruined Everything (Easter Egg - Things You need to Know About Chickenpox)


Things were so much easier when life consisted of being told something by an authoritative figure, after which you could go on indefinitely, believing that fact to be true.  That is how most of medicine has been taught and learned.  The trouble is that much of what we are told is either untrue or unfounded.  Of course to ruin it all, there in now a way to check up on what you are told.  That has made life very difficult for anyone in a medical educational role.

Let me give a non-medical example to illustrate my point.  A few years ago, after watching the film Guardians of the Galaxy, I was commenting on the way that Vin Diesel's role as an animated character was a departure from his roots in gritty action thrillers.  My daughter politely told me that this was untrue, since he had played the title role in the rather brilliantly animated Iron Giant film (1999).  Since I am big and she was little, I felt it only reasonable to set my daughter straight, pointing out that said film was intelligent and Vin Diesel was a hard core meat head who at that stage had not yet begun his career as an actor in any meaningful way.

In my childhood, that would have been the end of the matter.  Faced with such an argument I would have accepted my wrongness or at least agreed to differ with said parent.  This is no longer how these things play out and I was confronted immediately by my wiki-error and proved wrong.

Imagine if we should start to do that with what we think we know about anything in medicine.  Take chickenpox for example: Let's explore some of the things that you might have been told about one of the most common childhood infections.

1. Chickenpox (varicella) is a benign, self limiting viral illness

While that is mostly true, Chickenpox has a surprisingly bad track record.  here are a few chickenpox stats that may surprise you:

  • Hospital admission rate of up to 6 per 1000 cases (2)
  • Mortality of 2-3 per 100,000 cases (1,2)
  • Risk of death four times higher in infants (2)
  • 70% of deaths occur in otherwise healthy cases (2)

What causes these admissions and deaths?  It turns out that chickenpox has an alarming number of potential complications.  The most common complication of chickenpox infection is secondary bacterial infection.  This can be the obvious culprit: stapphylococcus aureus.  However probably more commonly and certainly more significantly, group A streptococcal (GAS) infection is the real enemy.  Children with chickenpox are particularly prone to this infection which accounts for the majority of varicella associated deaths.


Other acute and serious complications include encephalitis and pneumonia.  The morbidity and mortality of all of these has been significantly reduced where varicella vaccination has been introduced.

2. You should not give Ibuprofen to children who have chickenpox

If you haven't come across this chestnut then I apologise for being the bearer of bad and rather confounding news.  There has been a controversy about ibuprofen and chickenpox for a long time.  Around the same time that Vin Diesel was voicing the Iron Giant (1999), there was a case controlled study published in which a significant number of children with chickenpox developed necrotising faciitis. (3)  For whatever reason, the authors suspected a link with ibuprofen use and indeed found an association.

This has led many to recommend that ibuprofen is not used as an antipyretic for children with chickenpox.  I believe that the case for this avoidance is based on flawed information.  Firstly, there is the confirmation bias of the original work.  Some of the cases in the study were the same cases that led the authors to ask the question: 'Is there a link?'  Secondly, although it was a case controlled study, the children in the control group had less fever.  Could that be a confounder when looking for an association with an antipyretic one wonders...  Indeed, at the time ibuprofen was a prescribed drug.  In many ways, you could say that the conclusion could easily have been 'Children with chickenpox who were sick enough to see a doctor had a ten times greater risk of developing necrotising faciitis.'  Finally, the association (if there was one) was mainly with ibuprofen being given after there were signs of invasive GAS infection.

The case for avoiding ibuprofen in children with chickenpox is far from convincing.  I certainly don't think that anyone should be accused of bad medicine if they have used ibuprofen for a child with uncomplicated chickenpox.

My advice is this:  Use paracetamol as first line treatment for fever in children with chickenpox.  If a second antipyetic is being considered, ask 'Why does this child need a second medicine?'  Symptoms of uncomplicated chickenpox are normally controllable with one antipyretic.  If the child is unwell despite this, consider the possibility of a secondary infection.


3. Chickenpox causes a rash for a week and a fever for a few days and then it gets better

Except when it doesn't...

While the vast majority get better without complications, chickenpox causes a suprising number of children to get a rather unusual neurological condition: cerebellitis (also called post viral ataxia).  This is a post-infective phenomenon which tends to present in the weeks immediately after the infection, often as the lesions are well crusted or even fading.  Typically the child presents with ataxia.  Other symptoms include clumsiness and difficulty maintaining posture.  Nystagmus and other cerebellar signs may be obvious.  There is no treatment needed but children should be assessed by a specialist to confirm the diagnosis.  Imaging is not needed as long as there are no atypical features and the symptoms begin to improve after a couple of weeks. (4)


So, the internet ruins any attempt to hold onto our faith in simple facts.  This is partly because facts are rarely simple and often wrong.  All of the three bold statements above were things that I was told and believed at some point in my career.  Finding out the truth takes a little looking and a lot of thinking but you get to find out some worthwhile things along the way.  Or, you could just let an expert tell you the facts...

Edward Snelson
So very not an expert
@sailordoctor

References
  1. Atkinson, William (2011). Epidemiology and Prevention of Vaccine-Preventable Diseases (12 ed.). Public Health Foundation. pp. 301–323. ISBN 9780983263135
  2. Heininger, U., Varicella, The Lancet, Vol 368, Iss 9544, 14–20 Oct 2006, p1365–1376
  3. Zerr DM. et al., A case-control study of necrotizing fasciitis during primary varicella, Pediatrics. 1999 Apr;103(4 Pt 1):783-90.
  4. Nussinovitch M. et al., Post-infectious acute cerebellar ataxia in children, Clin Pediatr (Phila). 2003 Sep;42(7):581-4.


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