Friday, June 27, 2014

Paralysed

The other day I recieved a terrifying notification via email, advising me to be alert for evidence of polio in returned travellers.  This is due to upheaval in Syria, Pakistan and Afghanistan and a growing global antivaccination sentiment.  A crying shame as only a few short years ago we were incredibly close to declaring this planet polio free, an incredible legacy to pass onto our children.

In her day job your author does her best to see as many children as possible immunised against deadly diseases just like this one.  Now she will use this little hobby of hers to remind whatever audience she has exactly why vaccinations are so important.



Poliomylelitis is a virus which is spread between humans primarily via the faecal oral route. Ninety percent of the time it is asymptomatic.  Seven percent of the time it is a unpleasant flu like illness.  Three percent of the time it attacks the nervous system, causing paralysis with varying degrees of severity.  In bad cases it can lead to pauses in breathing known as apnoeas (the treatment for which was the notorious iron lung).  Because it was usually first encountered in childhood, it came to be known as infantile paralysis.  It was first described by the German orthopaedist Jakob Heine in 1840.  Polio is highly contagious and in endemic areas will infect almost everyone.

There is no cure for polio and treatment, even today, remains supportive only. 

Long term complications of polio (apart from death) include skeletal deformities and neuropathies.  Paralysis can be permanent.  Twenty five to fifty percent of people who recover from paralytic polio go on to suffer from post polio syndrome which is characterised by muscle weakness and fatigue.

Well known people who survived a bout of polio in their youth include Kim Beazley, Kerry Packer, Alan Alda, Gene Simmons, Desmond Tutu, Frieda Kahlo, Mia Farrow.  This is a list I could continue for days but in the interest of brevity I will cease. 

In the post war United States polio was one of the most important public health problems.  An epidemic in 1952 affected around 58,000 people leaving 3, 145 people dead, and over 21, 000 with some form of paralysis.  Most of the victims were children.   In Australia case numbers approached 10,000 per year in the latter part of the 1940s and early 1950s.   Millions of dollars of donations from from the March of Dimes program an organisation sponsored by President Roosevelt - himself a victim of polio - almost all went in support of research efforts for vaccination.

A man named Dr. Jonas Salk, a medical researcher who had previously worked on flu vaccines during WWII began working on polio vaccine research at the University of Pittsburgh.  His technique was to inject killed versions of the virus to allow the body to create antibodies.  He tested it on polio survivors, himself and his family, finally publishing in the journal of the American medical association and announcing on radio in March 1953.

 Jonas Salk gives his son Peter the Polio vaccine - March of Dimes foundation

In 1954 a huge clinical trial with the Salk vaccine and placebo began with over two million American school children, the largest medical experiment in history.  As soon as safety was established, a national vaccination program began in April 1955.  By 1961 and a mass immunisation campaign promoted by the march of dimes only 161 cases of polio were recorded in the United States.

A live polio vaccincation was also in development by Dr. Koprowski at the Wistar Institute and Dr. Sabin at the University of Cinicinatti.  As the population of the United States was largely immune to polio by that stage (thanks to Salk) Koprowski tested his vaccine in Northern Ireland and Sabin in Russia.

Based on trials - Sabin's vaccine was found to be the better one and it was licensed in August 1960.  It also had several advantages over Salk's vaccine - namely it conferred longer lasting immunity so boosters were not required, acted quickly, and could be given orally.  It was also lower cost to make and distribute.

The use of the Sabin vaccine eventually replaced the Salk vaccine in most countries.  Unfortunately what is known about the Sabin vaccine is it carries a small risk the Salk vaccine does not - a risk of vaccine induced polio.  This is very rare, generally quoted as about one in 750,000 vaccine recipients but probably even lower.  At a time when polio was so widespread and lethal the risk benefit profile was heavily in favour of the quicker, cheaper more effective immunisation.  This changed in most of the Western world and in the early 2000s, most switched to use an updated version of the Salk vaccination.  (This author remembers clearly being given her Sabin vaccination in high school.  It tasted terrible and she has just dated herself terribly).  Where polio is still endemic and that risk profile is different the World Health Organisation is still using the Sabin vaccine.

Today polio is all but wiped out in most of the world, an amazing legacy that has occurred in the last sixty years.

Imagine my horror when I see an article this morning saying polio virus has been found in a sewer at the world cup.

Vaccinate your kids and yourself - don't let this get a toe hold again.   It's really just that easy. 


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Journal of the American Medical Association
Author: Salk JE
URL: http://jama.ama-assn.org/
1953 vol 151 p 1081

http://www.historyofvaccines.org/content/timelines/polio

http://www.wired.com/2014/06/polio-brazil/

Science
2 June 2000: Vol. 288 no. 5471 pp. 1593-1594
DOI: 10.1126/science.288.5471.1593

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