Polio and Sanitation

KHAGARIA: On the sandy banks of Kosi river in north Bihar, a quiet crowd of several hundred people is waiting in the sizzling morning sun. A speck appears in the pale blue summer sky, rapidly growing in size — its a gleaming white helicopter. Within seconds it is hovering above the opposite bank, amidst the cornfields.

The crowd is awestruck at the monstrous machine as it settles down in billowing clouds of sand. Out comes the man everybody has been waiting to see — Bill Gates.

Bill Gates has come to find out why polio eradication is failing in Bihar. He asks questions about immunization strategies and tries to figure out what sort of technical problems are blocking universal vaccine delivery.

People complain of lack of basic health facilities…There are only 49 auxilliary nurse and midwives under the PHC, against a sanctioned strength of 76…So, the delivery of basic health services is itself a distant dream…The villagers hope against hope. Isn’t the spread of polio linked to lack of sanitation and basic health facilities? Gates acknowledges this fact but says that it is for the government to do the needful. “We are concentrating on the eradication of polio, which is achievable through vaccines,” he says. [1]

Polio epidemics first appeared in the mid-nineteenth century. Many doctors and scientists struggled with the mystery: why, as living conditions improved, did incidents of paralysis increase? Out of all the changes that came with modernity, improved sanitation was chosen as the change which caused polio to turn from a mild illness to one that left death and permanent damage in its wake.  Here is an excellent example  from a 2007 medical article which summarizes the concept:

Prior to the 20th century, virtually all children were infected with PV while still protected by maternal antibodies. In the 1900s, following the industrial revolution of the late 18th and early 19th centuries, improved sanitation practices led to an increase in the age at which children first encountered the virus, such that at exposure children were no longer protected by maternal antibodies. Consequently, epidemics of poliomyelitis surfaced . [2]

And this monograph:

Ironically, the advanced state of public hygiene in the U.S. and the rest of the developed world contributed to the polio epidemics of the 20th century. Polio is primarily a disease of infants and children. Before public hygiene developments, infants and young children became exposed to poliovirus, but their symptoms were mild and the exposure provided lasting immunity. With the advent of indoor plumbing and modern ideas about hygiene and sanitation, children were not exposed to the poliovirus in infancy and did not develop natural immunity. As a result, outbreaks of polio began to be seen in the mid-1800s. [3]

This theory came about primarily as a result of Sabin’s extensive research into polio in the developing world, where paralytic polio was found to be quite rare, in contrast to the rising epidemics of this disease in Europe and the United States. [4]

The reliability of the worldwide polio statistics in the early part of the 20th century is variable. Nevertheless Sabin’s survey of the literature turns up some fairly good data:  Japan, 1948, 1.2 cases per 100,000 population; a survey in Palestine between 1915-1934 found 20 times more cases in the Jewish than in the Moslem population; in the Philippines during 1944 and 1945, rates of 88 and 43 per 100,000 among the American troops and no cases or very rare instances among the Filipino children.  One of the most interesting examples are statistics collected in Hawaii during 1938 to 1947 comparing various ethnic groups living in the same neighborhoods and attending the same schools: rates per 100,000 vary from a high of 10.2 among the white population to a low of 1.3 among the Hawaiian population. [4]

Ardley describes a study by Gear which

isolated virus from the stools of African natives who had elevated titres of antibody to virus and no symptoms. The virus was shown to have been of high virulence and quite capable of producing paralysis when European troops entered such territories during the 1939-46 war, so that paralytic poliomyelitis became to them quite a serious hazard.[5]

In our previous article on acute flaccid paralysis, we noted that many cases which were called polio turned out not to be polio with more careful diagnosis and laboratory testing. There is actually a standard calculation of the rate of paralysis which will still occur in the absence of polio:

The global incidence rate of nonpolio AFP would be expected to be 1 per 100,000 among children under 15 years of age under conditions of optimal surveillance with complete case ascertainment. [6]

Compare this with the rates in non-Western populations found by Sabin: 1.2 cases per 100,000 in Japan, 1.3 cases per 100,000 among native Hawaiians between 1938 to 1947. It seems plausible that there may have been either few or no cases of polio among non-Western populations before the arrival of…what exactly?

The idea that sanitation caused outbreaks of polio could be called a scientific theory of sorts. Research into this theory has been limited. Karl Popper (see section 3 of linked article) developed the concept of “falsifiability” in scientific research, which demands that scientific theories make predictions and that those predictions should be capable of being proven wrong. [7] When Sabin presented his research in 1951, it would have been possible to formulate predictions about the future epidemics of polio in the developing world which might have either supported or disproved  his roughed out ideas. An obvious problem is the variety of changes which come along with modernization. It would be hard to find an area where only one factor changed. People don’t just get a water treatment plant and a sewage plant. They get hospitals, vaccinations, dietary changes, changes in social arrangements, changes in clothing, changes in education, changes in agricultural methods, changes in economic life, changes in exposure to chemicals…how in the world could it be demonstrated that improved sanitation was the sole factor which precipitated epidemics of polio? We quoted this, above:

Before public hygiene developments, infants and young children became exposed to poliovirus, but their symptoms were mild and the exposure provided lasting immunity. With the advent of indoor plumbing and modern ideas about hygiene and sanitation, children were not exposed to the poliovirus in infancy and did not develop natural immunity. As a result, outbreaks of polio began to be seen in the mid-1800s.

This statement makes two predictions:

1) Outbreaks of paralytic polio would begin in areas where plumbing was upgraded. In other words, the first outbreaks would occur in cities, not in rural villages. And only in cities where sanitary facilities had been upgraded.

2) Outbreaks of paralytic polio would first appear in older children not among infants or young children.

An overview by Dorothy M. Horstmann, Professor of Epidemiology and Pediatrics:

It is now well recognized that endemic poliomyelitis is world wide in distribution, and evolution of the disease as an epidemic one within the last century has followed a characteristic pattern. At first, a few small collections of cases are noted; then a higher than usual endemic rate for a few years is followed by severe epidemics with high attack rates. The age group attacked in endemic poliomyelitis and in early epidemics is the youngest-0-4 years, with 90 per cent of paralytic cases (particularly in urban areas) being under 5 years of age. Once this pattern of epidemicity begins, it is apparently irreversible unless preventive vaccination is carried out. As epidemics recur over a period of years and the average annual rate reaches 5 to 10 per 100,000 a shift in age incidence occurs, so that relatively fewer cases are in the youngest children, the peak often occurs in the 5-14 year group, and an increasing proportion of young adults is affected. This stage of development naturally poses an alarming situation since the disease is more severe and the mortality much higher with increasing age. [8]

Professor Horstmann clearly indicates that at least some of the paralytic cases were occurring in rural areas, although paralysis in babies seemed more common in the cities. She also points out that the first outbreaks of paralysis occurred not in older groups but in the infants and children under five years of age. Predictive power of the theory? Not so good.

We found papers which describe early outbreaks in Africa, Central America and South America. This article talks about the outbreak in Leopoldville which started in 1958. [9]

Paralytic poliomyelitis is endemic in the city; since 1951 there has been an average annual incidence of 63 cases, and a rate of 19.4 cases per 100,000 inhabitants. More than 80 % of the cases have occurred in African children less than 3 years old. [9] (emphasis added)

Was Leopoldville a city with modern sanitary arrangements? According to Table I, entire sections of the city still used pit privies in the 1950s. Overall, 73% of the housing in the city had such privies. [9]

Was paralytic polio appearing first among older children as the sanitation theory would suggest? No, as we see above, the majority of the cases were in small children, under 3 years of age.

Leopoldville was a fairly typical outbreak of paralytic polio in a developing country. The sanitation theory doesn’t match the actual facts.

The increasing outbreaks of polio in Africa and South America led eventually to the lameness surveys described in our previous article. The lameness surveys were used to justify the worldwide drive to eradicate polio which began in the late 1980s. No other explanation for the rise of paralytic polio has been put forward despite the inconsistencies of the sanitation narrative against the actual data worldwide and the continuing incidence of polio in areas with sanitation problems. Nathanson [10] did a detailed analysis of the theories and the actual data and also found large holes in the sanitation “dogma”. One of the assumptions supporting the sanitation theory is the idea of singular causation: that there must have been one factor which caused polio to move from mild to dangerous. However, it is quite possible that there is more than one factor which affects the ability of polio to invade the nervous system of human beings.

The sanitation hypothesis also fails to explain the very low incidence of paralytic polio, even in epidemics. As the sanitation theory story goes:  polio epidemics arise because of an increase in the population of susceptible individuals who haven’t been exposed during infancy. However, in practice, millions of supposedly susceptible people, exposed to polio, experienced the mildest of symptoms or no symptoms at all. Here are some examples of polio rates in countries where sanitation was supposedly delaying exposure during infancy and creating a large population of vulnerable children and adults.

From Sabin, 1951, [4]

In the non-epidemic periods, most of these rates are equivalent or close to the rate of nonpolio AFP which WHO expects in populations under the age of 15. Since the chart includes all ages, we are actually faced with rates of polio which may not even include any actual cases of polio. Except in the  epidemic years, of course.

Nathanson, in 1979, also puts up similar figures (next 4 charts) [10]:

Consider the following graph which shows that everyone eventually became a “polio” survivor. In spite of the theoretical susceptibility, most people continued to sail through exposure to polio, even if they didn’t get it in infancy. Why? What were the factors which left some people dead or paralyzed? Why were some people vulnerable to severe consequences from this illness and, why, even during epidemics, were most people able to pass through polio without paralysis? In fact, most people passed through polio epidemics without becoming noticeably ill at all.

Despite the data we have analyzed, which is widely available even to laypeople,  we have been told that better hygiene was the cause of paralytic polio in the west. To the medical profession this seemed to be the best available explanation for the anomaly between countries with sanitation and epidemics of paralytic polio, and the lack of clinical polio in countries without sanitation. This story continued to be told, despite the increasing outbreaks of paralytic polio in areas where sanitation was incredibly bad.

Nowadays, as described in the newspaper story with which this article opens, people at polio ground zero in India and elsewhere, believe that the primary driver of polio is the lack of sanitation and clean water.

The puzzle pieces do not fit together.

Furthermore, we don’t hear much about the fact that:

The Indian Medical Association Sub-Committee’s report on Polio Eradication Initiative which noted that in 2006:

despite repeated doses of oral polio vaccine (OPV) during repeated mass pulse immunization campaigns for communities, there were an alarming 1,600 cases of vaccine-induced polio.

Some of these children had been given more than 15 doses of Oral Polio Vaccine. Why weren’t they protected by poor sanitation?

Because sanitation, or lack of it, was not the determinant of who will get polio, and it never has been.

That old dogma doesn’t hold water, because in the same countries where clinical polio was considered a “white man’s” problem in 1951, polio eventually became common among a population which used to be immune. Most of these countries can’t blame the change on the introduction of sanitation, clean water and raised living standards, unfortunately.

So what are some of the factors which are NOT being talked about, and which  might explain why, in developed countries, polio went from an endemic illness which rarely or never resulted in paralysis, to an epidemic disease that crippled thousands? And might those same NOT talked about factors also explain the increase in polio in developing countries from 1960 onwards?

Next: Polio Provoked.

[1] http://epaper.timesofindia.com/Default/Scripting/ArticleWin.asp?From=Archive&Source=Page&Skin=TOINEW&BaseHref=TOIPU/2010/05/14&PageLabel=16&EntityId=Ar01500&ViewMode=HTML&GZ=T

[2] Epidemics to Eradication: the Modern History of Poliomyelitis, Nidia H De Jesus, Virology Journal, 2007, 470. http://www.virologyj.com/content/pdf/1743-422X-4-70.pdf

[3] Polio, Massachusetts Society for Medical Research Inc., 2004. http://www.msmr.org/documents/MSMRDi…August2004.pdf

[4] Paralytic Consequences of Poliomyelitis Infection in Different Parts of the World and in Different Population Groups, Albert B. Sabin, American Journal of Public Health, Vol. 41, Oct. 1951. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1525657/pdf/amjphnation00428-0010.pdf

[5] Topical Aspects of Poliomyelitis, John Ardley, The Journal of the Royal Society for the Promotion of Health. 1956; 76: 767-779 http://rsh.sagepub.com/content/vol76/issue12/

[6] Differential Diagnosis of Acute Flaccid Paralysis and Its Role in Poliomyelitis Surveillance, Arthur Marx, Jonathan D. Glass, and Roland W. Sutter. Epidemiologic Reviews, Vol. 22, No. 2, 2000. http://epirev.oxfordjournals.org/cgi/reprint/22/2/298.pdf

[7] Karl Popper, Stanford Encyclopedia of Philosophy, first published Thu Nov 13, 1997; substantive revision Feb 9, 2009, accessed on June 21, 2010. http://plato.stanford.edu/entries/popper/

[8] Epidemiology of Poliomyelitis and Allied Diseases-1963, Dorothy M. Horstmann, The Journal of Biology and Medicine, Vol. 36, August 1963. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2604573/pdf/yjbm00599-0011.pdf

[9] Vaccination with the CHAT Strain of Type 1 Attenuated Poliomyelitis Virus in Leopoldville, Belgian Congo: 1. Description of the City, its History of Poliomyelitis, and the Plan of the Vaccination Campaign, Andre Lebrun, et. al., Bulletin of the World Health Organization, 1960, 22, 203-213. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2555313/pdf/bullwho00332-0012.pdf

[10] The Epidemiology of Poliomyelitis: Enigmas Surrounding its Appearance, Epidemicity, and Disappearance, Neal Nathanson, John R. Martin, American Journal of Epidemiology, Vol. 110, No. 6, 1979. http://www.ncbi.nlm.nih.gov/pubmed/400274

[11] Nature Medicine, volume 14, Number 1, January 2008 http://www.nature.com/nm/journal/v14/n1/full/nm0108-9.html


7 Comments on Polio and Sanitation

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  1. Sid Offit on Fri, 2nd Jul 2010 9:19 am
  2. Great post. The cleanliness theory is clearly absurd.

  3. Peter on Sun, 9th Oct 2011 4:22 pm
  4. Also Sabin criticized the “sanitation theory” in this paper: Vaccination against poliomyelitis in economically underdeveloped countries – http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2395893/

    “Contrary to oft-expressed dogma, high rates of paralytic poliomyelitis are occurring annually in regions with high infant mortality rates, continuing undernutrition, and absence of basic sanitary facilities. “

  5. admin on Mon, 10th Oct 2011 6:51 pm
  6. Great find, thanks! Note that he doesn’t wonder why polio is increasing in these countries if it isn’t due to improved sanitation. Whatever the cause, the best solution is always vaccination!

  7. Kathy on Mon, 10th Oct 2011 7:13 pm
  8. Did you read the 7-part series from Age of Autism on what they believe caused the polio epidemic? Here is part 7 (which has links to the other 6 parts). Quite an interesting theory. Essentially, they say that the virus that causes polio has existed for millennia, and is usually benign (and still is) but it takes something else to trigger it into the paralytic disease we know and fear today. Originally, it was high exposure to lead or arsenic; then with the use of a lead-arsenic spray to kill gypsy moths, many people were affected; and as that spray fell out of favor, DDT was taken up and used. Interesting concept; I’d love to know what you think of the idea.

  9. admin on Tue, 11th Oct 2011 7:29 am
  10. Hi Kathy,
    Well, they got quite a bit right. If you read through the comments on the series, note points raised by Hilary Butler and a couple of other people for the parts they missed. Overall, I was quite pleased with the series.

    [...] de casos de parálisis producidos por otras causas que fueron atribuidos a la poliomielitis. En el tercer artículo nos fijamos en una de las explicaciones para el aumento de la poliomielitis paralítica [...]

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