How Did the Polio Virus Live Among Populations Without an Epidemic?
Polio (Poliomyelitis) has some unusual characteristics that make it one of the more odd diseases for medicine and society to deal with. It lived among humans for thousands of years, but, for the most part, it had little effect on people. Until the mid-1800s in Europe, epidemics were either so limited that they weren't recognized, or they were not recorded.
Polio would be seen in the occasional infant or very small child, who would be afflicted with a fever and paralysis (either temporary or permanent), or a fever and breathing difficulties that led to death. (Because it was rarely seen in adults, one of the names later given to it was "infantile paralysis".)
As paralysis and respiratory failure had quite a few potential causes, and because few children at a time suffered these symptoms, the cause was never specifically attributed to anything but a fever. But polio was maintained within populations throughout the world for thousands of years.
Egyptian mummies have been found who were thought to have paralysis from polio, and a stone tablet from 15th century B.C. contains a picture of an Egyptian man with a withered limb. Polio was noticed in the late 1700s by a British doctor, Michael Underwood, who described it as a "debility of the lower extremities".
The first detailed recorded case of polio was by Sir Walter Scott, who was infected in 1773. His doctor listed the episode as a "teething fever," but his own record of what happened to him confirmed that it was polio. He was left with a permanently weakened leg.
Then, in Europe in the mid-1800s, the first outbreaks began. They were limited, but people noticed clusters of paralysis associated with fevers in infants and small children. The first time it was noticed in the United States was as a small outbreak in Louisiana in the mid-1800s.
However, it was not noted in numbers again in the U.S. until the mid-1890s. The first recognized epidemic was in Vermont, where 132 cases, including 18 deaths, were recorded. (Scientists didn't understand yet that the known cases represented about 2% of the people who were actually infected with polio.)
Numerous limited epidemics were then recorded, with increasing frequency and with a higher number of cases. Then in 1916, an outbreak of over 27,000 known cases and over 6,000 deaths occurred (which meant about 130,000 people could have been infected). Brooklyn, New York, was the hardest hit location for that outbreak, where over 2,000 died. That was the beginning of the large epidemics, which occurred periodically in Europe and the U.S., and didn't end until the populations were vaccinated many decades later.
Unusual incidents of the outbreak were seen. Polio was known to affect infants and children mainly. However, during WWII, medical experts were baffled to see adult soldiers with polio, but only those stationed in the Middle East. Meanwhile, the local population around them seemed untouched.
As the Soviet Union modernized, polio struck Russia with a major epidemic in the mid-20th century. The epidemic was frightening enough that even in the midst of the cold war, Russian doctors turned to the U.S. for vaccines.
Polio epidemics caused notices to be posted
How Could Having More Sanitary Conditions Cause Polio Epidemics?
The oddest characteristic of the polio infection was that the cleaner people became in their ordinary lives, and the better the sanitation, the more infants and small children came down with the disease. This wasn't recognized as a link until about the mid-20th century.
It had been proven, and public health officials had taught us, that being cleaner meant having fewer waterborne and food-borne diseases. This was true of major killers like typhoid and cholera, along with a vast range of other contagious diseases and parasites. For example, many thousands of infants and small children were saved from dying of dysentery after water became cleaner.
However, though it wouldn't be understood until the soldiers with polio were examined in WWII by Dr. Jonas Salk, being cleaner made us more susceptible to polio. Mothers washed their hands more, the food was cleaner, the water was cleaner, bodies were cleaner, babies were cleaner, and houses were cleaner. How could that possibly trigger epidemics?
When the answer was finally found, it was a logical one for this disease. When a baby is born, it has antibodies from its mother, passed to it in the womb during the last few months of pregnancy, and in the first breast milk, the colostrum. If the mother has been exposed to a disease - in this case, polio - in her lifetime and has successfully fought it off, the baby is temporarily protected by receiving her antibodies.
Before improved sanitation, modern plumbing and improved personal cleanliness, the mother would have been born with her mother's antibodies, then would have been exposed very early in life by food, water or contamination via the lack of cleanliness around her. She would still have been protected by her mother's antibodies when she was exposed, so she could handle the disease - with few or no symptoms - and would have developed her own antibodies without anyone noticing.
So most people were immunized by exposure in the first few months of life, and were safe from polio. Only very weak or otherwise immune-compromised babies were not able to fight off the second, often paralyzing, stage of the disease.
After babies were born into a cleaner environment, a baby would have its mother's antibodies, but then they would fade away after a few months. If the baby wasn't exposed to polio, when she grew up and had her baby, she would have no polio antibodies to pass on to her baby. Also, if the environment was cleaner and had no endemic polio virus in it, her baby would not have contact with polio in early infancy. (If polio is contracted in infancy or early childhood, it is more likely to be less severe.)
The link to cleanliness wasn't understood until the soldiers in the Middle East during WWII became infected with polio. They had lived in a cleaner environment, so hadn't been exposed to polio. When they arrived, they were wide open for polio infection. They ate the food, drank the water, mixed with the locals, and, for some, polio paralysis or even death was the result.
Dr. Jonas Salk, who had been working on a polio vaccination, had enlisted in the Medical Corps during WWII. He was sent to the Middle East and found the reason behind this odd set of circumstances.
Polio symptoms include paralyzing the neurons that control breathing
The course that polio infection will take is uncertain
Poliomyelitis means "inflammation of the gray matter". That name was given it when scientists realized that it destroyed only motor nerves.
When a baby reaches about six months, it needs to have some of its own antibodies. If someone is exposed to polio without the mother's antibodies to protect him or her, one of several results could develop.
1. The most common is that the infection causes antibodies to develop, but there are no symptoms, and the person doesn't even know that infection occurred. That happens over 90% of the time.
2. The second, but much less common result is that the person becomes ill with fever, digestive upset and possibly a cough, but the polio virus stays in the lymph glands in the digestive system and the throat, and doesn't reach the central nervous system (CNS), so people tend to think they (or their babies) probably have the flu. This infection has no lasting effects, except immunity.
3. However, the third possible result occurs when polio reaches its second stage - infection of the central nervous system (CNS). Polio is potentially devastating when it moves from capillaries in the intestines out to the bloodstream, and reaches the CNS, where it damages motor neurons. (When it reaches nerves, it focuses only on motor neurons, not on sensory neurons, so victims can still feel.)
The person has more severe symptoms, along with muscle stiffness and headache, and maybe some temporary weakness or paralysis, but the symptoms disappear as the fever subsides. The weakness or paralysis usually indicates that this is polio.
4. For an unfortunate few, about 1 person in 200 who are exposed, the fourth result is that polio reaches the CNS and paralyzes enough motor neurons that control anywhere from one limb to (depending on the type of polio and how far up the spinal cord it attacks) the whole spinal cord. The nerves damaged may include those that control breathing and swallowing.
5. If the infection reaches motor neurons that are high in the spinal cord or in the brain, death is the likely result.
Polio symptoms could be reduced or eliminated, depending on the level of nerve damage
Not all motor nerve damage caused by polio is noticeable, or permanent
Even when polio reaches the CNS, if it destroys less than 20% of the motor neurons in any area, the loss of motor skill is not noticeable by the casual observer.
However, for those who have little or no resistance, about 1 out of every two hundred people exposed, over 20% of the neurons needed for movement will be destroyed where the virus has attacked the CNS, and partial or total paralysis will occur.
Many times, with proper physical therapy, the weakness or even paralysis can be reversed or reduced. However, if 50% or more of the motor neurons are destroyed, the paralysis is permanent. As a result, people who were placed in a wheelchair or iron lung in the 1950s would still be in them if they were alive 50 years later.
The person who did the most in helping people to recover from paralysis was Elizabeth Kenney, a nurse from Australia, who came to the U.S. and Europe and showed physical therapists how to apply wet hot packs and to use certain massage techniques. (Because paralyzed victims could still feel, they described these painful massages as daily torture.)
Her methods and teaching were responsible for thousands of polio victims leaving wheelchairs and even iron lungs behind, and returning to normal life. Before her treatments were introduced, the standard practice was to immobilize patients for long periods of time to prevent their limbs from contorting as the connective tissue shorted. That method had guaranteed permanent disability.
Post-Polio Syndrome returns decades after the initial infection
If polio has reached the CNS during infection, it has been found to re-emerge many decades after paralysis as Post-Polio Syndrome. If someone had paralysis while infected, the motor neurons will show a new weakening, as if the paralysis was returning. Unlike the initial infection, this is not a true infection, so the person affected is not contagious. When this condition appears, patients are usually provided with physical therapy in an attempt to strengthen their muscles once more and to try to counteract the weakness.
Children are most often affected by polio
How contagious is polio?
Even though people were unaware for centuries that it existed, the polio virus is very contagious. Unlike other major diseases, it lived well for thousands of years as a mainly unnoticed endemic, or locally maintained, disease throughout the temperate and tropical areas of the world.
When sanitation improved and the populations began to suffer epidemics, they weren't certain for several decades how it was spread. So any single case could easily result in an epidemic large enough to cause thousands of paralyzed victims.
Polio is a virus. While it can't replicate outside of the body, it can live outside of the body for two months. (Polio can live in swimming pools, lakes and other environments where people wouldn't expect to encounter it.)
As it is replicating both in the throat and the intestines, polio is spread through coughing or sneezing, and by food, water and surfaces contaminated by fecal matter.
In most diseases, only people who show the symptoms, such as a rash, are contagious, or "shed" the disease. However, every person who has been exposed to polio is shedding polio virus in both saliva and stool. The polio virus can be shed from a few days after exposure, long before the person feels any symptoms - if any are felt - to a week after the polio infection has developed, where symptoms may be felt. The phase where symptoms may be felt lasts about a week to 10 days. The total time the virus can be shed by one exposed person can easily be over a month.
There are two basic types of polio vaccine, dead virus and live but weakened (attenuated) virus. Not only is polio virus shed after exposure, it is shed by those who are vaccinated with the live but weakened polio virus. For example, in 1973, the former lieutenant governor of Virginia was partially paralyzed when he was exposed to polio by changing the diapers of his baby after it had been vaccinated with live virus.
When polio infection is found in an unvaccinated household, it is usually found in 100% of the occupants, even though most, or even all, of them show no symptoms. The ease of spreading the virus comes with a sneeze, a cough, poorly washed hands, sharing a cup or utensil, contaminated surfaces, etc. A baby is always putting its hands into its mouth, so it is most easily infected.
Polio survives in temperate climate zones during summer and autumn, and is present in tropical zones year-round.
For about 20 years after the 1916 epidemic of polio that began in New York, scientists thought it gained entrance to the body through the nose. Later, it was found that, while a sneeze or cough can cause entrance through the nose, entrance was primarily through the mouth.
The incubation period for polio can be as long as 35 days, and most people who contract it don't have symptoms. So polio is a champion when it comes to mechanisms for spreading a disease. It is highly contagious, it has a long period of time where the person is contagious but doesn't know he or she is infected, and when a person should be showing symptoms - because most people don't have symptoms - that person will very likely still not be aware of being contagious.
A rare photo of Salk and Sabin together
Polio struck FDR, then he struck back
When FDR was paralyzed by polio, it changed everything
In August 1921, at the age of 39, Franklin Delano Roosevelt was infected with polio, and became permanently paralyzed from the waist down. (There are some disputed opinions about what he was infected with, but his assumed polio case changed the course of polio for the rest of the world.) As he struggled with his paralysis and tried to find ways to overcome it, he became convinced that hydrotherapy was a good treatment, and bought a resort in Warm Springs, Georgia. He turned this into a treatment center for polio victims, which is now still used as a rehabilitation center. Then, as the need grew, and he won the presidency, he asked attorney Basil O'Connor to take it over. While O'Connor was at first reluctant to accept, he soon became dedicated to raising funds to treat, then to eradicated polio.
The foundation started by Roosevelt and O'Connor became the March Of Dimes Foundation and major campaigns raised funds around the country. These donations paid for hospitalization and on-going treatment of polio victims in the U.S. They also paid for research that later led to immunization against polio.
As the cost of caring for paralyzed polio victims increased and more progress was made with possible vaccinations, people began to realize that, while treatment needed to continue for those already afflicted, the focus needed to change to immunization for everyone.
Dr. Jonas Salk led the research responsible for the dead polio vaccine, which must be injected. This vaccine was introduced in 1954, and was used for several years prior to introduction in about 1962 of the live vaccine. Dr. Albert Sabin led the research for the live vaccine, which can be given orally. This vaccine contains weakened, or attenuated, virus. Both the dead vaccine and the weakened live vaccine are used today, depending on the access to medically trained volunteers and to needed equipment.
The focus on treating polio changed to eradicating polio
If everyone is immunized polio can be eradicated
Why is polio considered a disease that can be eradicated?
Because polio is so dependent on direct human-to-human transmission, it is one of the diseases that can be eradicated. While it was shown, during a 1966 polio epidemic, to infect the Gombe chimps being studied by Jane Goodall, it did not persist in their environment. It also can't be spread by mosquitoes or other insects, as malaria and yellow fever are.
Because polio becomes more virulent for the population with increased sanitation, which prevents other major epidemics of killing diseases, it must be eradicated. That it doesn't have devastating results for the vast majority of people who are infected isn't a reason for it not to be chosen for the expensive and time-consuming project of global eradication. When it strikes and is successful in reaching the CNS, it does so in the young, and, if they survive, they are left crippled for the remainder of their lives.
Like most viruses, polio can't be cured. But, in spite of being highly contagious, it can be eradicated. If everyone in an area is inoculated and becomes immune, then the polio is destroyed as it enters any human body, and has nowhere to replicate (reproduce). After a few months, it dies out in the environment. (This sounds easy, but is a difficult and complicated achievement.)
Polio has been eradicated in most of the world. (The last case of polio in the U.S. was in 1979.)
Polio cases 1980 to 2010
As of Jan 13, 2012, India had been free of wild polio for one year.
Eradicating polio isn't easy and it isn't cheap
In 1988, the WHO, UNICEF, Rotary International and the CDC began the Global Eradication Project. At that time, approximately 1,000 children per day were being crippled by polio. Since that time, over 20 million volunteers have vaccinated over 2 billion children in twenty countries, and have almost succeeded in polio eradication. As of 2011, less than 1,000 cases were reported globally per year.
The Bill & Melinda Gates Foundation, with the help of Warren Buffett's huge donation, joined the fight several years ago to make polio the second major disease to be eradicated from the planet (smallpox was the first). They have added millions of dollars to this campaign, and are working in SE Asia to bring other billionaires forward to fill the gap in funds needed for this project. There are still hundreds of millions of dollars needed.
As of 2012, polio is endemic (maintained naturally) in only three countries in the world; Afghanistan, Pakistan and Nigeria. If polio can be eradicated in those three countries, it will be defeated.
However, due to its highly contagious nature and the fact that global travel re-introduces diseases to the populations around the world, vaccination for polio is still needed. This was proven recently when pilgrims going from the still-infected countries to Mecca for the Islamic Hag caused minor outbreaks in several countries. These outbreaks were immediately stopped by an intensive vaccination campaign. Before polio was eradicated in northern India, an infection caused people travelling to Russia and Europe to infect others. These polio "wildfires" will have to be caught and put out over and over again until all of polio is eradicated.
Because dead vaccine must be injected, and is safer to use, it is normally used in countries where medical help is available. In other countries, live vaccine is used.
Eradication in the third world has been a complex and difficult endeavor. Attenuated live vaccine is used, for three main reasons.
1. It can be distributed as two drops on the tongue by minimally trained members of the community.
2. It is much less expensive to produce for the millions who still need the vaccine.
3. As long as live wild virus exists in the environment, shedding weakened live virus is not as much of a problem as it would be if there was no wild virus already present. It would be highly preferable to have people infected with the shed weakened live virus than the strong wild virus.
There are three types of wild virus, PV1, PV2 and PV3. All of them paralyze when they reach the CNS. However, one of them, PV2, has been confirmed as eradicated. However, the live vaccine PV2 is still being distributed as part of the three-part live polio vaccine. In some areas, it has mutated and is now causing a few cases of polio to be reported and confirmed. Of the other two, PV1 is most common and most associated with paralysis.
The vaccine that has been given includes all three types of polio. However, this has the disadvantage of less virus of each type being in the oral drops, and the types having to compete with each other in the body - fewer antibodies are produced for each type. With wild PV2 gone, attenuated PV2 mutating and causing some cases of polio, and PV1 clearly known as the most common, discussions have progressed that favor giving only PV1 vaccine in areas where PV3 is not common. Immunity to PV1 would progress more quickly, then a follow-up vaccine with PV3 could be given if it was found in that area.
The type of polio for every polio case is known now, because every polio case has blood drawn and shipped to a special lab. This lab tests the sample and can tell not only what type of polio it is, but, using the specific genetic code of each polio, where the polio originated. This not only confirms whether or not the polio was local, but, if it wasn't local, where it came from.
There are many difficulties in completing vaccination in the remaining countries. Extremely mountainous areas in Afghanistan and Pakistan make reaching populations difficult. People travel freely across the Pakistan/Afghanistan border not only for war but because the local mountain people don't really think of it as an official border. War and rebellion in all three countries also interfere, and can make conditions unsafe for volunteers.
In Nigeria, a rumor that the vaccine rendered babies sterile or gave them AIDS caused major resistance and long delays in vaccination, and resulted in some neighboring countries having new outbreaks of polio when they had been free of it. Engaging the leaders more heavily in Nigeria countered this rumor and finally caused it to be ignored.
In many areas, especially if the children are in generally poor health, due to other chronic diseases or malnutrition, they may need more than the standard two doses of vaccination to be immune to polio. In India, which is the most recent country to be taken off the list of countries with active polio, some areas required up to eight oral vaccinations before all of the children were immune.
The eradication of polio is very close. However, it can fail completely if these last three countries are not cleared of polio, and it will quickly spread to other countries around the world. As polio cannot be cured, inoculation for polio would then be the only possible way to control it. The other option would be to go back to filthy conditions for everyone, and to begin contracting all of the other diseases that have been controlled by cleanliness.
Bruce Aylward: How we'll stop polio for good as of may 24, 2011
You might also like:
- List of poliomyelitis survivors - Wikipedia, the free encyclopedia
Wikipedia list of famous polio survivors
Update - As of January 2017
- Rare Strain of Polio Worries Pakistan, Global Community
The country has launched an intensified immunization effort after the discovery of the rare Type 2 strain of polio
- United Nations News Centre - UN agency hails new polio vaccination regimen in South-East Asia that c
Amid a global shortage of injectable inactivated polio vaccines (IPV), a new inoculation regimen, employed by governments in the South-East Asian region, involving two fractional vaccine doses – each about a fifth of a full dose – p
- Vaccine shortage threatens polio eradication | The Independent
The international campaign to eradicate polio, which has vaccinated 2.5 billion people since it began in 1988 – nearly all of them children – has faced one setback after another. Its goal of wiping out the disease, which was meant to happen in 2000,
Comments about Polio Virus and Its Odd History
Gargi09 on September 04, 2018:
Very informative atleast I always thought polio was because of bad hygiene ,this is just opposite.
Karla Iverson (author) from Oregon on February 24, 2013:
Thank you so much, sdelandtsheer!
Sébastien De Landtsheer from Ferrara, Italy on February 22, 2013:
Fantastic research and great writing! Please continue being awesome!
Karla Iverson (author) from Oregon on September 01, 2012:
What a nice comment! Thank you, Writer Fox.
Writer Fox from the wadi near the little river on September 01, 2012:
This is an awesome article! I hope Google finds it!
Karla Iverson (author) from Oregon on June 22, 2012:
Thank you, KoffeeKlatch Gals. What a wonderful compliment! The idea of eradicating a disease as devastating as Polio is fascinating to me, and I've been watching the struggle to get those last countries clear of it.
Susan Hazelton from Northern New York on June 22, 2012:
Absolutely fascinating. I learned a great deal from your article. Your research is unbelieveable. And your pictures are fantastic, they fit right in with the writing. Up and everything except funny.
Karla Iverson (author) from Oregon on June 02, 2012:
That's an interesting thought, but each virus has its own receptor or receptors in the body. That's why we're susceptible to it and why we develop specific antibodies to it. Thanks for your comment, parwatisingari.
parwatisingari from India on June 02, 2012:
has anyone considered that other infections existing might have neutralized polio?
Karla Iverson (author) from Oregon on June 02, 2012:
Thank you. I'm glad you liked it, CWanamaker.
Christopher Wanamaker from Arizona on June 01, 2012:
The story of Polio is very interesting indeed! Thanks for the good read.
Karla Iverson (author) from Oregon on June 01, 2012:
I was also fascinated by the backward way that polio seemed to work from all of the other diseases. Being cleaner was supposed to make everyone healthier! Thank you, leahlefler.
Karla Iverson (author) from Oregon on June 01, 2012:
Thank you, Marcy! I remember the vaccination line, too, at our National Guard Armory. It was hot, the town swimming pool was closed and our parents wouldn't let us go to the lake.
Leah Lefler from Western New York on June 01, 2012:
Wow, this is fascinating! I love the hieroglyphic picture showing an ancient Egyptian with polio - I also think it is very interesting how the improved sanitary conditions of the 20th century led to outbreaks, since infants weren't exposed to the virus and their mother's antibodies early in life. What a fantastic article!
Marcy Goodfleisch from Planet Earth on June 01, 2012:
This is such a thorough and well-written hub! I remember the March of Dimes, and I went to school with a few kids who had contracted polio before the vaccines were developed. We don't realize today how frightened parents were of that disease years ago (justifiably so). Excellent hub - voted up and up!
Karla Iverson (author) from Oregon on May 31, 2012:
Thanks for stopping by, McGilwriter.
Karla Iverson (author) from Oregon on May 31, 2012:
Hi, phoenix2327. Thanks for the great rating, and I'm glad you enjoyed it. I had a lot of fun with this one.
McGilwriter from Florida on May 31, 2012:
interesting, I enjoy reading historical items. Thanks for sharing
Zulma Burgos-Dudgeon from United Kingdom on May 31, 2012:
This is a fantastic hub. I was engrossed from the start and learned so much. What an intriguing history this disease has.
Voted up, useful, awesome and interesting. Socially shared.
Karla Iverson (author) from Oregon on May 31, 2012:
Thank you, Vellur. It's a fascinating topic, and I finally had to stop reading about it and write my own piece. I can see where books come from about polio.
Nithya Venkat from Dubai on May 30, 2012:
Oh my this a treasure trove of information about polio. You have presented the facts so very well and covered every angle.You have researched thoroughly, voted up.