This is the second in a series of thought pieces on the poliovirus and Zika virus, and how sometimes history has a way of repeating itself. The first article was “Poliovirus and Zika: What’s Past is Prologue.”
Imagine 100 people who have symptoms of severe paralysis somewhere on their body… say, their legs. They are all permanently paralyzed, but some of the people have one or more of the following conditions which can produce paralysis similar to polio:
Acute Flaccid Paralysis (AFP); Arsenic Poisoning; Bilious Remittent Fever; Chinese Paralytic Syndrome; Cholera Morbus virus; Coxsackie virus; DDT Poisoning; ECHO; Enteroviral Encephalopathy; Epidemic Cholera; Ergotism; Famine Fever; Guillain-Barré Syndrome; Hand, Foot, and Mouth Disease; Inhibitory Palsy; Intermittent Fever; Lead Poisoning; Myalgic Encephalomyelitis (Chronic Fatigue Syndrome); Post-Polio Syndrome; Reye’s Syndrome; Spinal Apoplexy; Spinal Meningitis; Transverse Myelitis; Traumatic Neuritis; Undiagnosed Congenital Syphilis; Viral or Aseptic Meningitis; Worm Fever… and “provocation of limb paralysis by intramuscular injections of many types, including a variety of vaccines.”1 2
How would you know which of these individuals had “polio”? The answer is all those who test positive for the presence of the “poliovirus.” If they don’t test positive for poliovirus, then they don’t have “polio.” They’re still paralyzed for good, but they are not diagnosed as having polio paralysis.
Now, remember that there’s a possibility that even those individuals who are paralyzed and test positive for the poliovirus may not have been paralyzed by the poliovirus. No one knows exactly why less than 1% of people who become infected with poliovirus and develop complications that lead to some form of temporary or permanent paralysis, and the more than 99% who become infected with poliovirus either do not exhibit any clinical symptoms or have minor symptoms, such as fever, sore throat, headache and fatigue, and do not become paralyzed.3 4
Thus, it is entirely possible—even likely—that the people who become paralyzed and test positive for poliovirus could have become paralyzed as a result of something else, perhaps one of the more than two dozen conditions listed above. What if, for example, 50 of the 100 paralyzed people had gone for a long swim in a lake highly contaminated with arsenic, DDT and lead from nearby industries a few days prior to developing the paralysis? What if they also tested positive for poliovirus? What is the likelihood that all of them developed complications of poliovirus infection, as opposed to becoming paralyzed by exposure to arsenic, DDT or lead poisoning? Is simply testing positive for poliovirus the real test of whether poliovirus is to blame for the paralysis?
If scientists still don’t know why some people with the poliovirus become paralyzed and others don’t, and if we know that the poliovirus in more than 99% of people who carry it is either completely harmless or mild, then how do we even know that the poliovirus is ever the culprit (and not something else) when paralysis does occur? Is it scientific to assume that a person who becomes paralyzed and tests positive for the poliovirus has, in fact, been paralyzed by the poliovirus?
Think of the Zika virus that is making so much news in both the national and international media. We know that only 1 in 5 people who get Zika ever show any symptoms. Other symptoms include “fever, rash, joint pain, or conjunctivitis (red eyes)” and “muscle pain and headache.”4
According to the U.S. Centers for Disease Control and Prevention (CDC), “People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. For this reason, many people might not realize they have been infected.”5
So Zika virus, like poliovirus, is relatively harmless. Yet, scientists, medical researchers, and public health officials are feverishly trying to establish a causal relationship between Zika and the cases of microcephaly (smaller than normal baby heads and associated neurological damage) in Brazil.
Before long, Zika will become synonymous with microcephaly—much like polio has become synonymous with severe paralysis. As with cases of paralysis in the presence of the poliovirus, there is a tendency to want to believe that microcephaly is caused by Zika merely because of the presence of the Zika virus.
But correlation, no matter how strong it may be, does not equal causation. Science doesn’t doesn’t work that way.
According to the CDC, microcephaly is caused by a number of factors, including:
- Certain infections during pregnancy, such as rubella, toxoplasmosis, or cytomegalovirus
- Severe malnutrition, meaning a lack of nutrients or not getting enough food
- Exposure to harmful substances, such as alcohol, certain drugs, or toxic chemicals
- Interruption of the blood supply to the baby’s brain during development6
As there are many causes of the symptoms that we have come to associate with polio, there are many causes of microcephaly. For some reason, however, we have remained strangely fixated on poliovirus, and now Zika virus.
1 Humphries S. Smoke, Mirrors, and the “Disappearance” Of Polio. International Medical Council on Vaccination Nov. 17, 2011.
2 Humphries S, Bystrianyk R. Dissolving Illusions: Disease, Vaccines, and The Forgotten History. July 27, 2013.
3 Polio. GlobalHealth.gov.
4 Mayo Clinic. Polio Symptoms. May 11, 2014.
5 Centers for Disease Control and Prevention. Zika Virus. CDC.gov.
6 CDC. Birth Defects. CDC.gov.