Polio (also called poliomyelitis) is a contagious, historically devastating disease that was virtually eliminated from the Western hemisphere in the second half of the 20th century. Although polio has been around since ancient times, its most extensive outbreak occurred in the first half of the 1900s until the polio vaccine was introduced in 1955.
At the height of the polio epidemic in 1952, nearly 60,000 cases with more than 3,000 deaths were reported in the United States alone. However, with widespread vaccination, wild-type polio, or polio occurring through natural infection, was eliminated from the United States by 1979 and the Western hemisphere by 1991.
Polio is a viral illness that, in about 95% of cases, actually produces no symptoms at all (called asymptomatic polio). In the 4% to 8% of cases in which there are symptoms (called symptomatic polio), the illness appears in three forms:
People who have abortive polio or nonparalytic polio usually make a full recovery. However, paralytic polio, as its name implies, causes muscle paralysis — and can even result in death.
In paralytic polio, the virus leaves the intestinal tract and enters the bloodstream, attacking the nerves (in abortive or asymptomatic polio, the virus usually doesn't get past the intestinal tract). The virus may affect the nerves governing the muscles in the limbs and the muscles necessary for breathing, causing respiratory difficulty and paralysis of the arms and legs.
Polio is transmitted primarily through the ingestion of material contaminated with the virus found in stool (poop). Not washing hands after using the bathroom and drinking contaminated water were common culprits in the transmission of the disease.
In the United States, it's currently recommended that children have four doses of inactivated polio vaccination (IPV) between the ages of 2 months and 6 years.
By 1964, the oral polio vaccine (OPV) had become the recommended vaccine. OPV allowed large populations to be immunized because it was easy to administer, and it provided "contact" immunization, which means that an unimmunized person who came in contact with a recently immunized child might become immune, too.
The problem with OPV was that, in very rare cases, paralytic polio could develop either in immunized children or in those who came in contact with them. Since 1979 (when wild polio was eliminated in the United States), the approximately 10 cases per year of polio seen in this country were traced to OPV.
IPV is a vaccine that stimulates the immune system of the body (through production of antibodies) to fight the virus if it comes in contact with it. IPV cannot cause polio.
In an effort to eradicate all polio, including those cases associated with the vaccine, the Centers for Disease Control and Prevention (CDC) decided to make IPV the only vaccine given in the United States. Currently, the CDC and American Academy of Pediatrics (AAP) recommend three spaced doses of IPV given before the age of 18 months, and an IPV booster given between the ages of 4 to 6, when children are entering school.
If you're planning to travel outside the United States, particularly to Africa and Asia (where polio still exists), be sure that you and your kids have received a complete set of polio vaccinations.
Although the acute illness usually lasts less than 2 weeks, damage to the nerves could last a lifetime. In the past, some patients with polio never regained full use of their limbs, which would appear withered. Those who did fully recover might go on to develop post-polio syndrome (PPS) as many as 30 to 40 years after contracting polio. In PPS, the damage done to the nerves during the disease causes an acceleration of the normal, gradual weakness due to aging.
During the height of the polio epidemic, the standard treatment involved placing a patient with paralysis of the breathing muscles in an "iron lung" — a large machine that actually pushed and pulled the chest muscles to make them work. The damaged limbs were often kept immobilized because of the confinement of the iron lung. In countries where polio is still a concern, ventilators and some iron lungs are still used.
Historically, home treatment for paralytic polio and abortive polio with neurological symptoms wasn't sufficient. However, asymptomatic and mild cases of abortive polio with no neurological symptoms were usually treated like the flu, with plenty of fluids and bed rest.
Health groups are working toward wiping out polio throughout the world, and much progress has been made. But several countries still have polio circulating, which means that the virus could occur in others. If the polio virus reaches a country where not enough people have been immunized, it could spread from person to person, as has happened in some countries in Africa and Asia. So until it has been eliminated worldwide, it's important to continue vaccinating kids against polio.
Reviewed by: Nicole A. Green, MD
Date reviewed: January 2014
|Centers for Disease Control and Prevention (CDC) The CDC (the national public health institute of the United States) promotes health and quality of life by preventing and controlling disease, injury, and disability.|
|American Academy of Pediatrics (AAP) The AAP is committed to the health and well-being of infants, adolescents, and young adults. The website offers news articles and tips on health for families.|
|Immunization Action Coalition This organization is a source of childhood, adolescent, and adult immunization information as well as hepatitis B educational materials.|
|World Health Organization (WHO) WHO, the United Nations' specialized agency, works to give people worldwide the highest possible level of health - physically, mentally, and socially.|
|Frequently Asked Questions About Immunizations Immunizations have protected millions of children from potentially deadly diseases. Learn about immunizations and find out exactly what they do - and what they don't.|
|A Kid's Guide to Shots If you're old enough to read this, you've probably had most of your shots. But even bigger kids may need a shot once in a while. Find out more about them in this article for kids.|
|Meningitis Meningitis (inflammation of the membranes that cover the brain and spinal cord) is treatable, but can be serious. So it's important to know the symptoms and get prompt diagnosis and treatment.|
|Immunization Schedule Which vaccines does your child need to receive and when? Use this immunization schedule as a handy reference.|
|Your Child's Immunizations Immunizations protect your child from potentially fatal diseases. Find out what vaccines your child needs to grow up healthy.|
|Your Child's Immunizations: Polio Vaccine (IPV) Find out when and why your child needs to get this vaccine.|
|Immunizations Missing out on shots puts you at more serious risk than you might think. That one little "ouch" moment protects you from some major health problems.|
|Wiping Out Polio To most, polio is a distant memory. But the disease has never been wiped out in three countries, which means outbreaks in other places are possible. Find out how to help all kids be immunized.|
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