Poliomyelitis (POH-lee-o-my-uh-LYE-tis), or polio, is a disorder caused by the poliovirus and involves damage of nerve cells. It may lead to weakness and deterioration of the muscles and sometimes paralysis. Thanks to an extremely successful vaccination * program, this disease has disappeared from the United States and much of the world, although it still exists in some countries.
Poliovirus, part of the enterovirus * group, makes its home in the alimentary canal, which includes the mouth, esophagus, stomach, intestines, colon, and rectum; but when the viral infection spreads it can destroy nerve cells that make muscles work. These damaged nerve cells, called motor neurons, cannot rebuild themselves. As a result, the body's muscles no longer function correctly.
Types of paralytic polio include spinal, bulbar (BUL-bar), and bulbospinal (bul-boh-SPY-nul). The spinal type is most common, affecting the muscles of the legs, trunk, and neck. The bulbar form involves nerves of the brain stem * and can cause problems with breathing, talking, and swallowing. Bulbospinal polio is a combination of the first two types.
Polio has been essentially wiped out in the United States and many other developed countries following the introduction of a polio vaccine in 1955. Before that, polio occurred in epidemic *
Poliovirus is extremely contagious and can pass easily from person to person. The virus typically is found in feces and can spread when people touch contaminated objects and then touch the mouth or nose, or handle food without washing their hands first. The virus can live in feces for weeks, making the spread of infection difficult to control. It can also spread through contact with tiny drops of fluid from a sick person's mouth or nose, or by drinking contaminated water. After entering the mouth or nose, the virus multiplies in the throat or gastrointestinal tract and eventually invades the bloodstream, where it can move to other parts of the body. In a very small number of people, about 1 to 2 percent, the virus invades the central nervous system (the brain and spinal cord) where it can cause paralysis.
The infection is most contagious 7 to 10 days before symptoms begin and for the same period after they appear. The virus spreads more readily in areas with poor sanitation.
A doctor may suspect polio in a sick patient with paralysis, particularly if the person has not been immunized against polio. The doctor may follow up with questions about recent travel, because while the polio vaccine has wiped out the disease in the United States, polio still occurs in some other countries. During a physical examination, a doctor looks at the extent of the muscle paralysis and may take samples of blood, bowel movements, fluid from the throat, or cerebrospinal fluid * and have them tested for the virus.
There was no cure for polio as of 2016. Doctors instead focus on easing a patient's symptoms, which includes controlling pain and muscle spasms, and matching supportive care to the patient's muscle weakness. For abortive cases and many nonparalytic cases of polio, a doctor typically recommends rest, fluids, and pain medication, as well as moist heat on muscles to ease stiffness. The doctor may also prescribe antibiotics to treat urinary tract and other bacterial infections that can occur in patients with polio.
Patients with severe cases of polio, particularly the paralytic form, often require hospitalization. In the 1940s and 1950s, medical professionals placed patients inside metal tanks called iron lungs, which assisted their breathing. Although medical technology has progressed since then, many people who have polio still need machines called ventilators * to help them breathe as they recover, as well as additional supportive care. Patients with paralytic polio may need physical therapy, crutches, leg braces, or surgery to help them regain their strength and movement.
Although a diagnosis of paralytic polio is a frightening one, most survivors go on to lead fulfilling lives. The violinist Itzhak Perlman, who caught the virus at four years of age and wears leg braces, is one example. Franklin D. Roosevelt, who got polio at the age of 39, went on to become president of the United States.
The polio vaccine is the best way to prevent the disease, and its use has eliminated polio from the United States and much of the world. A worldwide vaccination program has been put in place, but the disease persists in such places as Afghanistan, India, Pakistan, and numerous countries in Africa. In many of these countries, poor sanitation and crowded conditions contribute to the spread of the disease just as health officials are trying to get everyone immunized.
In the early 21st century, IPV was the only polio vaccine used in the United States, and it does not cause VAPP. Children might have a sore spot where they receive the shot, but side effects from the vaccine are very rare. Children receive IPV routinely as part of the childhood immunization schedule. Most adults who were vaccinated as children do not need to receive the vaccine again. People traveling to places where polio is still found (such as Africa and Asia); lab workers who handle poliovirus; and medical professionals who care for patients with polio may need a repeat vaccination. If polio is wiped out worldwide, then immunization against polio will no longer be needed.
See also Meningitis • Paralysis • Vaccines and Immunization • Viral Infections
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* vaccination (vak-sih-NAY-shun), also called immunization, is giving, usually by an injection, a preparation of killed or weakened germs, or a part of a germ or product it produces, to prevent or lessen the severity of disease caused by that germ.
* enterovirus (en-tuh-ro-VY-rus) is a group of viruses that can infect the human gastrointestinal tract and spread through the body, causing a number of symptoms.
* brain stem is the part of the brain that connects to the spinal cord. The brain stem controls the basic functions of life, such as breathing, heart rate, and blood pressure.
* epidemic (eh-pih-DEH-mik) is an outbreak of disease, especially infectious disease, in which the number of cases suddenly becomes far greater than usual. Usually epidemics are outbreaks of diseases in specific regions, whereas widespread epidemics are called pandemics.
* cerebrospinal fluid (seh-reebro-SPY-nuhl floo-id) is the fluid that surrounds the brain and spinal cord.
* ventilator (VEN-tuh-lay-ter) is a machine used to support or control a person's breathing.
* pneumonia (nu-MO-nyah) is inflammation of the lungs.
* kidney stones are hard structures that form in the urinary tract. These structures are composed of crystallized chemicals that have separated from the urine. They can obstruct the flow of urine and cause tissue damage and pain as the body attempts to pass the stones through the urinary tract and out of the body.