What is polio

Polio or poliomyelitis, is a crippling and potentially deadly and highly infectious disease caused by the poliovirus. The poliovirus spreads from person to person and can invade an infected person’s brain and spinal cord, causing total paralysis (can’t move parts of the body) in a matter of hours. The poliovirus is transmitted by person-to-person spread mainly through the fecal-oral route or less frequently, by a common vehicle (for example, contaminated water or food) and multiplies in the intestine. Most people infected with the polio virus have no symptoms; however, for the less than 1% who develop paralysis it may result in permanent disability and even death. Initial symptoms are fever, fatigue, headache, vomiting, stiffness of the neck and pain in the limbs. 1 in 200 polio infections leads to irreversible paralysis (usually in the legs). Among those paralyzed, 5% to 10% die when their breathing muscles become immobilized. Polio mainly affects children under 5 years of age.

The term “polio” or “poliomyelitis” is defined as the paralytic disease. So only people with the paralytic infection are considered to have the polio disease.

• The risk of lifelong paralysis is very serious. Even children who seem to fully recover can develop new muscle pain, weakness, or paralysis as adults, 15 to 40 years later (post-polio syndrome).
• About 2 to 10 children out of 100 who have paralysis from polio die because the virus affects the muscles that help them breathe.

There is no cure for polio, but there are safe and effective polio vaccines. Therefore, the strategy to eradicate polio is based on preventing infection by immunizing every child to stop transmission and ultimately make the world polio free. In 1988, the World Health Assembly adopted a resolution for the worldwide eradication of polio. It marked the launch of the Global Polio Eradication Initiative ¹. Polio cases have decreased by over 99% since 1988, from an estimated 350 000 cases in more than 125 endemic countries then, to 37 reported cases in 2016. Of the 3 strains of wild poliovirus (type 1, type 2, and type 3), wild poliovirus type 2 was eradicated in 1999 and no case of wild poliovirus type 3 has been found since the last reported case in Nigeria in November 2012.

Polio facts

• Polio (poliomyelitis) mainly affects children under 5 years of age.
• 1 in 200 infections leads to irreversible paralysis. Among those paralyzed, 5% to 10% die when their breathing muscles become immobilized.
• Polio cases have decreased by over 99% since 1988, from an estimated 350 000 cases then, to 37 reported cases in 2016. As a result of the global effort to eradicate the disease, more than 16 million people have been saved from paralysis.
• As long as a single child remains infected, children in all countries are at risk of contracting polio. Failure to eradicate polio from these last remaining strongholds could result in as many as 200 000 new cases every year, within 10 years, all over the world.
• In most countries, the global effort has expanded capacities to tackle other infectious diseases by building effective surveillance and immunization systems.

Do people still get polio in the United States?

No, the United States has been polio-free for more than 30 years, but the disease still occurs in other parts of the world. It would only take one person with polio traveling from another country to bring polio back to the United States ².

How is polio spread

Poliovirus only infects humans. Poliovirus is very contagious and spreads through person-to-person contact. The virus lives in an infected person’s throat and intestines. It enters the body through the mouth and spreads through contact with the feces (poop) of an infected person and, though less common, through droplets from a sneeze or cough. You can get infected with poliovirus if you have feces on your hands and you touch your mouth. Also, you can get infected if you put in your mouth objects like toys that are contaminated with feces (poop).

An infected person may spread the virus to others immediately before and about 1 to 2 weeks after symptoms appear. The virus can live in an infected person’s feces for many weeks. It can contaminate food and water in unsanitary conditions.

People who don’t have symptoms can still pass the virus to others and make them sick.

Polio causes

Poliovirus can be transmitted through direct contact with someone infected with the virus or, less commonly, through contaminated food and water. People carrying the poliovirus can spread the virus for weeks in their feces. People who have the virus but don’t have symptoms can pass the virus to others.

Risk factors for poliomyelitis

Polio mainly affects children younger than 5. However, anyone who hasn’t been vaccinated is at risk of developing the disease.

Polio prevention

The most effective way to prevent polio is vaccination. Polio vaccine protects children by preparing their bodies to fight the polio virus. Almost all children (99 children out of 100) who get all the recommended doses of vaccine will be protected from polio.

There are two types of vaccine that can prevent polio: inactivated poliovirus vaccine (IPV) and oral poliovirus vaccine (OPV). Only IPV has been used in the United States since 2000; OPV is still used throughout much of the world.

Polio Vaccines

There are two types of vaccine that protect against polio:

• Inactivated poliovirus vaccine (IPV) and
• Oral poliovirus vaccine (OPV).

IPV (inactivated poliovirus vaccine) is given as an injection in the leg or arm, depending on the patient’s age. Polio vaccine may be given at the same time as other vaccines. Most people should get polio vaccine when they are children. Children get 4 doses of IPV at these ages: 2 months, 4 months, 6-18 months, and a booster dose at 4-6 years. OPV has not been used in the United States since 2000 but is still used in many parts of the world.

Who Should Get Polio Vaccine?

Infants and Children

Children in the United States should get inactivated polio vaccine (IPV) to protect against polio, or poliomyelitis. They should get four doses total, with one dose at each of the following ages:

• 2 months old
• 4 months old
• 6 through 18 months old
• 4 through 6 years old

Children who will be traveling to a country where the risk of getting polio is greater should complete the series before leaving for their trip. If a child cannot complete the routine series before leaving, an accelerated schedule is recommended as follows:

• 1 dose at age 6 weeks or older
• a second dose 4 or more weeks after the first dose
• a third dose 4 or more weeks after the second dose
• a fourth dose 6 or more months after the third dose

If the accelerated schedule cannot be completed before leaving, the remaining doses should be given in the affected country, or upon returning home, at the intervals recommended in the accelerated schedule. In addition, children completing the accelerated schedule should still receive a dose of IPV at 4 years old or older, as long as it has been at least 6 months after the last dose.

Adults

Most adults do not need polio vaccine because they were already vaccinated as children. But three groups of adults are at higher risk and should consider polio vaccination in the following situations:

• You are traveling to a country where the risk of getting polio is greater. Ask your healthcare provider for specific information on whether you need to be vaccinated.
• You are working in a laboratory and handling specimens that might contain polioviruses.
• You are a healthcare worker treating patients who could have polio or have close contact with a person who could be infected with poliovirus.

Adults in these three groups who have never been vaccinated against polio should get 3 doses of IPV:

• The first dose at any time,
• The second dose 1 to 2 months later,
• The third dose 6 to 12 months after the second.

Adults in these three groups who have had 1 or 2 doses of polio vaccine in the past should get the remaining 1 or 2 doses. It doesn’t matter how long it has been since the earlier dose(s).

Adults who are at increased risk of exposure to poliovirus and who have previously completed a routine series of polio vaccine (IPV or OPV) can receive one lifetime booster dose of IPV.

Who Should NOT Get Polio Vaccine?

Tell the person who is giving the vaccine:

• If the person getting the vaccine has any severe, life-threatening allergies.
• If you ever had a life-threatening allergic reaction after a dose of IPV, or have a severe allergy to any part of this vaccine, you may be advised not to get vaccinated. Ask your health care provider if you want information about vaccine components.
• If the person getting the vaccine is not feeling well.
• If you have a mild illness, such as a cold, you can probably get the vaccine today. If you are moderately or severely ill, you should probably wait until you recover. Your doctor can advise you.

How Well Does the Polio Vaccine Work?

Inactivated poliovirus vaccine (IPV), which is the only polio vaccine that has been given in the United States since 2000, protects almost all children (99 out of 100) who get all the recommended doses. For best protection, children should get four doses of polio vaccine.

What are the Possible Side Effects of Polio Vaccine?

With any medicine, including vaccines, there is a chance of side effects. These are usually mild and go away on their own, but serious reactions are also possible.

Some people who get IPV get a sore spot where the shot was given. IPV has not been known to cause serious problems, and most people do not have any problems with it.

Other problems that could happen after this vaccine:

• People sometimes faint after a medical procedure, including vaccination. Sitting or lying down for about 15 minutes can help prevent fainting and injuries caused by a fall. Tell your provider if you feel dizzy, or have vision changes or ringing in the ears.
• Some people get shoulder pain that can be more severe and longer-lasting than the more routine soreness that can follow injections. This happens very rarely.
• Any medication can cause a severe allergic reaction. Such reactions from a vaccine are very rare, estimated at about 1 in a million doses, and would happen within a few minutes to a few hours after the vaccination.

As with any medicine, there is a very remote chance of a vaccine causing a serious injury or death.

Polio symptoms

Most people who get infected with poliovirus (about 72 out of 100) will not have any visible symptoms.

About 1 out of 4 people with poliovirus infection will have flu-like symptoms that may include:

• Sore throat
• Fever
• Tiredness
• Nausea
• Headache
• Stomach pain

These symptoms usually last 2 to 5 days then go away on their own.

In rare cases, poliovirus infection can be very serious. About 1 out of 200 people will have weakness or paralysis in their arms, legs, or both. This paralysis or weakness can last a lifetime.

A smaller proportion of people with poliovirus infection will develop other more serious symptoms that affect the brain and spinal cord:

• Paresthesia (feeling of pins and needles in the legs)
• Meningitis (infection of the covering of the spinal cord and/or brain) occurs in about 1 out of 25 people with poliovirus infection
• Paralysis (can’t move parts of the body) or weakness in the arms, legs, or both, occurs in about 1 out of 200 people with poliovirus infection

Paralysis is the most severe symptom associated with polio because it can lead to permanent disability and death. Between 2 and 10 out of 100 people who have paralysis from poliovirus infection die because the virus affects the muscles that help them breathe.

Even children who seem to fully recover can develop new muscle pain, weakness, or paralysis as adults, 15 to 40 years later. This is called post-polio syndrome.

Post-polio Syndrome

Post-polio syndrome is a condition that can affect polio survivors decades after they recover from their initial poliovirus infection. It is characterized by a set of health problems, such as muscle weakness, fatigue (mental and physical), and pain from joint deterioration, that begins about 15 to 40 years after the initial poliovirus infection. Post-polio syndrome affects between 25 and 40 out of every 100 polio survivors.

Some people with Post-polio syndrome have only minor symptoms, while others develop more visible muscle weakness and atrophy (a decrease in muscle size). Post-polio syndrome is rarely life-threatening, but the symptoms can make it difficult for an affected person to function independently.

Unlike poliovirus, Post-polio syndrome is not contagious. Only a polio survivor can develop Post-polio syndrome.

Post-polio syndrome is a cluster of disabling signs and symptoms that affect some people years after having polio. Common signs and symptoms include:

• Progressive muscle or joint weakness and pain
• Fatigue
• Muscle wasting (atrophy)
• Breathing or swallowing problems
• Sleep-related breathing disorders, such as sleep apnea
• Decreased tolerance of cold temperatures

Polio diagnosis

Doctors often recognize polio by symptoms, such as neck and back stiffness, abnormal reflexes, and difficulty swallowing and breathing. To confirm the diagnosis, a sample of throat secretions, stool or a colorless fluid that surrounds your brain and spinal cord (cerebrospinal fluid) is checked for poliovirus.

Polio treatment

There’s currently no cure for polio. Treatment focuses on supporting bodily functions and reducing the risk of long-term problems while the body fights off the infection.

This can include bed rest in hospital, painkillers, breathing support and regular stretches or exercises to prevent problems with the muscles and joints.

If you’re left with long-term problems as a result of a polio infection, you’ll probably need ongoing treatment and support.

This may include physiotherapy to help with any movement problems, devices such as splints and braces to support weak limbs or joints, occupational therapy to help you adapt to any difficulties, and possibly surgery to correct any deformities.

Supportive treatments include:

• Pain relievers
• Portable ventilators to assist breathing
• Moderate exercise (physical therapy) to prevent deformity and loss of muscle function

1. http://polioeradication.org/[↩]
2. Polio and the Vaccine (Shot) to Prevent It. https://www.cdc.gov/vaccines/parents/diseases/child/polio.html[↩]