The Polio Story
by Portsmouth University, retired lecturer in Medical Microbiology, Tim Mason PhD
WSHOM lecture of Nov 24th 2018
One of the great values of the West Sussex History of Medicine Society lectures — at least from my perspective — is that they provide much food for thought. I always come away with many new questions that stimulate further research and I often make connections between ideas that I had previously seen as unrelated. Today was particularly rich grounds, as Tim Mason tackled the history of Polio, including the catastrophic outbreaks in the 1940s and 50s as well as 1916 in the USA; and the development of the vaccines which were credited with polio’s eradication in the 20th century.
The origin of polio, Mason reminds us, is lost in the mists of time. There are, however, indications that the disease was afflicting humanity as far back as Ancient Egypt, where its paralytic symptoms appear to have been depicted on engravings such as this one, dated to about 1500 BC.
The virus that we believe causes the disease has three forms, all of which have been identified in the nerve tissue of victims. Below is a coloured electron micrograph of the virus:
Poliovirus, pictured in this coloured transmission electron micrograph, is transmitted via direct person-to-person contact with infected mucus, phlegm or faeces. Symptoms can include fever; fatigue; muscle pain or weakness; stiff neck and back; and difficulty swallowing or breathing. It is important to remember that many people with polio are asymptomatic, but can still spread the virus to others. (Image: Public Domain )
We believe that humanity is on the brink of being rid of this awful disease, once and for all, and the vaccination programme that started in 1955 with Jonas Salk’s injectable inactivated virus vaccine, progressing to the more easily administered oral polio vaccine developed by Albert Sabin and commercialised in 1961 is accredited with the great reduction in diagnoses of ‘paralytic polio’ across the world.
When looking at images of the extraordinary treatments that were used to manage polio, the desire to be rid of it is entirely laudable, as were the many attempts to counter the muscle wasting, which was the main symptoms of the disease, due to nerve damage in one or other part. Contraptions to brace limbs were created, and massage/rubbing treatments and of course the infamous ‘iron lung’ for the bulbar form of polio (which paralyses the diaphragm) have all been utilised, with the latter representing a particularly daunting image of the disease and the need to conquer it.
Apparently, one chap was in an ‘iron lung’ for 43 years! The image below is probably a marketing shot, rather than an actual ward, as the noise of so many iron lungs would have been unbearable. More on the subject of marketing later…
The viruses that are believed to result in the symptom picture known as ‘polio’ is an enterovirus, i.e. gut-dwelling, and is transferred mostly through the faecal/oral route, though droplets/breath can also convey it, to a lesser degree.
Most infections with the virus go unnoticed as it is killed off and rendered harmless in over 95% of infections. Indeed we have probably all been exposed to Poliovirus without realising it, as our immune system simply saw it off, as it has evolved to do over the thousands of years the virus and humans have co-existed on earth.
Unfortunately, in some people the virus manages to survive in the lymph nodes and gets into the blood where it is circulated, causing unspecific symptoms, like fever and headache, until being cleared in the vast majority of cases, with just 5% of these individuals succumbing to classic polio. In these few cases, the virus finds its way to the motor neurons of the spinal cord where it causes varying degrees of neurological deficit, the most common being leg muscle weakness, spasms and pain, and in some, permanent paralysis of the limbs in question. In a tiny proportion, the virus effects part of the brain stem which is responsible for the most basic life maintenance system, i.e. respiration, and the results of this can be devastating, hence the iron lung.
As most of my readers will know, it was the 1940s and 50s that saw the most striking rise in the incidence of paralytic polio, and it was these that lead to the efforts to develop a vaccine. But interestingly, the worst year for polio in the United States was thirty years earlier, in 1916, when New York suffered an extremely severe summer epidemic; 8,900 cases of paralysis were logged, with 2,448 deaths! (Around 25%). The epidemic spread to other states, with a further 23,000 cases and some 5,000 deaths attributed to the poliovirus.
This paper, from 2011 discusses the probable origins of that appalling epidemic, which seems to have been forgotten, overshadowed as it was by the 1918 influenza epidemic, and then the mid-century polio story.
The author’s conclusion is that this worst-of-all polio epidemics was due to the development a highly virulent strain of the virus in a laboratory which was at the geographic centre of the outbreak. If he is right, then it was the scientists that caused this particular horror story! The somewhat neurotoxic virus was ‘potentized’ by a process of injecting it into the spinal cord of monkeys, again and again, until it had become super-specialised to nerve tissue. The results were deadly, and probably spread by workers at the lab who performed the vivisection, as apparently they were ill trained individuals. Well, whose fault was that?
Polio and DDT
Getting into a bit of my own research here… There are interesting theories about the sudden increase in paralytic polio from 1946 to 1957, which links them epidemiologically and mechanistically to an increase in pesticide use in general, and DDT in particular. We now know such chemicals have multiple toxic effects on humans with many being neurotoxic. One can hardly blame the scientists for their efforts, however, as there had been continuous waves of typhus for example (which is louse-borne) creating calls to ‘do something!’ The graph below shows data for England and Wales from 1912 to 1963.
As you can see by following the pink line, the incidence of polio was within certain bounds between 1912 and 1945, i.e. around 500 to 1,750 cases annually, but it only went over 1000 cases three times in this thirty-three year period. Then suddenly the number leaps, all at once, to 7,400 cases in 1946, back down to under 2,000 in 1947 but even higher in 1950 at about 7,850 cases at its peak, eventually dropping down to normal levels again by 1960. Note, these are cases only, not deaths or even permanent paralysis, just cases, as diagnosed by doctors of the time, within the diagnostic criteria of the time, which was, I believe, ‘…one or more weak or paralysed limbs for at least a 24 hour period...’ (Later this was to change to ‘..two or more limbs, for at least 20 days’. Changing the diagnostic criteria like this is incredibly common in medicine, and leads to confusion in the epidemiological data, for example, making diseases treatments look more effective than they really were.)
But I would like to draw your attention to the other lines on this graph. In 1945 DDT was introduced to the market, and was heavily promoted to the public. It was widely used by individuals and local councils in the year prior to the huge increase in polio incidence. Municipal authorities sprayed DDT on everything, and everywhere, whether children, animals or others were present or not.
Soldiers’ clothes were sprayed inside and out, while they were in them. Rivers, parks, farms and farm workers, school playgrounds, front gardens, streets, everywhere was sprayed with gay abandon, and DDT was promoted widely, with posters, songs, advertising hoardings, and in magazines and newspapers, with tag lines like “DDT is good for meee”.
One of the things that has puzzled researchers is that, unlike almost all other diseases, polio affected the children of the middle classes at a higher rate than amongst the poor. Might this have been because these parents could afford to ‘protect’ their children with more DDT products, like the ‘DDT infused wall paper,’? We now know that DDT disrupts not only neurons, but the reproductive and immune systems which would make children especially vulnerable as they are still developing.
Why did Polio affect middle-class families?
Two other factors are considered significant in the sudden increase in polio:
1) The dramatic change in infant feeding from the usual instinctive breast feeding that all babies had received historically, and which is naturally endowed with a plethora of protective molecules and stimulators of the new baby’s developmental needs, to, by the 1940s a 25% take-up of the early attempts at ‘infant formula’, and sweetened evaporated milk, which was heavily marketed to young mums, as better and easier than breast feeding. Images of healthy-looking smiling babies and mums were very lucrative. The sales ploy of including a doctor’s endorsement was a clincher, no doubt, in the ad below! The switch away from breast feeding would have left babies without the polio antibodies that breast milk would have provided.
2) Tonsillectomies had become fashionable and, it turns out, polio was twice as common in children without tonsils than those with them. In 1927 80,000 tonsillectomies were performed on British children. Indeed it was the most common reason for a child to be in hospital. This paper (below) published in the American Journal of Public Health in 1954 addresses the data available on this issue, and two hypotheses are mentioned, a) that the polio virus might have been residing in the tonsils at the time of the tonsillectomy, and by performing the operation they were released into the blood stream or b) that having no tonsils rendered children more vulnerable to the virus, especially to the bulbar form, which is responsible for the respiratory paralysis which can lead to the iron lung scenario, and deaths.
One study demonstrating this was based on 2,669 cases of polio in 1946 in Minnesota which found that 71.4% of the bulbar cases (which numbered 535, the rest being spinal forms) had had tonsillectomies at some time prior to their paralytic illness. It is well worth reading this paper, which has all the references that my readers will likely want to cross check.
This paper also mentions the notable fact that children who contracted polio were from the more affluent strata of society, who could not only afford DDT wallpaper, but tonsillectomies too! This supports the theory that parents with sufficient means who went out of their way to protect their children from diseases may inadvertently have made their offspring more vulnerable to polio. It is a salutary thought that those who preyed on such protective instincts for commercial ends may be with us today. What can you think of that is proffered with smiles and science today that our race had no need for over evolutionary time? Suggestions in the comments box below please.
Polio and diet
Wealthier families who ate more sugar in their diets, also had a higher incidence of polio. Not only does sugar reduce the amount of white blood cells available to fight pathogens, but the sugar refining methods back then involved all sorts of chemicals such as disinfectants as well as quicklime.
A trial performed in North Carolina in 1948 by US naval surgeon Dr Benjamin Sandler, was very effective at reducing the incidence of polio. As a result of his findings he convinced newspapers to promote a low-carbohydrate diet in North Carolina, which parents read and applied in their families, as no other options were being suggested to them at the time. And, lo and behold, the polio incidence went from one of the highest in the country to one of the lowest.
In 1951 Dr Sandler published a book about his theories of nutrition called Diet Prevents Polio (preceding Pure White and Deadly by John Yudkin by 21 years!) but the U. S. government banned it! Unfortunately, the book is currently out of print, however, one chapter is available online and can be read here.
Another look at the polio vaccine
So just how much credit should go to the polio vaccine? On the UK polio incidence graph that we looked at earlier, it appears as though the incidence of polio dropped to its lowest point in the century as polio vaccination rates increased. But, there are several other contributing factors that may have affected the change in recorded incidence of polio.
In 1954 doctors were directed to record a diagnosis of paralytic poliomyelitis in a patient if they had symptoms for 24 hours, in one or more limbs. These criteria, however, were subsequently revised such that a diagnosis then required at least two limbs to be affected, for at least 10 days, which was then extended to 20 days, and later to 50 days, and later still to 70 days! As you can appreciate, this reclassification alone would lead to an apparent drop in incidence, without any change in disease incidence.
Another way in which Polio cases may be overlooked is by diagnosing them as a different disease label. The similarity between polio and the condition we call Guillain-Barre Syndrome has not been lost on researchers. This paper from 1990 delineates the diagnostic criteria of GBS, and as you will see, they are virtually identical to those used for identifying polio a few decades earlier. (Assessment of Current Diagnostic Criteria for Guillain-Barré Syndrome – Asbury et al, 1990)
Likewise, another diagnosis, that of Acute Flaccid Paralysis is also very similar in presentation and outcome to polio, as this 1995 World Health Organisation Bulletin discusses: Epidemiology and clinical characteristics of acute flaccid paralysis associated with non-polio enterovirus isolation: the experience in the Americas. Dietz et al, 1995.
Clearly the overlaps between these conditions are many, and it may be that there has been a bit of sleight of hand going on in order to massage the statistics, to make it look as though the polio vaccination campaign has been a wondrous success, when in truth greater nutritional status globally — which has taken place at precisely the same time as the drop in polio incidence — is the real reason for a reduction in this dreadful disease.
Added to that, the change in terminology that doctors are now directed to use may be helping to keep polio reporting down, whilst, unfortunately, Acute Flaccid Paralysis and Guillain-Barre Syndrome have gone up. These far less powerful disease names, in the public mind, may have muddied the waters. Also note, all three of these paralytic diseases are, ironically, recognised side-effects of various vaccines.
[EDIT – 23rd November 2019]
I am adding this as I have just seen an abstract from a paper that was published by a research team in India in the International Journal for Environmental Research and Public Health in August 2018 (PMID 30111741). They have found that although no case of polio has been diagnosed in India since 2011, the rate of so-called Non-Polio-Acute-Flacid-Paralysis has gone up, and then fluctuated along with the amount of Oral Polio Vaccine doses that are given, in ‘pulsed campaigns’ in that country. The more doses of OPV given, the higher the rate of NPAFP (or simply AFP, as was mentioned in the article above).
Then I read an article from August 2018 by a paediatrician, Jacob Puliyel from St Stephen’s Hospital, Delhi. He claims that over 490,000 new cases of AFP were logged between 2010 and 2017. That seems like an awful lot of paralysed people for India to have to deal with.
So the question here is – Is the oral polio vaccine causing polio/AFP, and does the chance of developing such symptoms rise as the number of doses of OPV increases?