Poliomyelitis is a disorder caused by a viral infection. The virus, known as poliovirus, infects nerves. This infection can lead to temporary paralysis or, in more severe cases, permanent paralysis or death.

Poliomyelitis is a communicable disease caused by infection with the poliovirus. Transmission of the virus occurs by direct person-to-person contact, by contact with infected secretions from the nose or mouth, or by contact with infected feces.

The virus enters through the mouth and nose, multiplies in the throat and intestinal tract, and then is absorbed and spread through the blood and lymph system. Incubation (the time from being infected with the virus to developing symptoms of disease) ranges from 5 to 35 days (average 7 to 14 days).

Risks include:

• Travel to an area that has experienced a polio outbreak
• Lack of immunization against polio and subsequent exposure to a case of polio

In areas that had an outbreak, the more susceptible populations include children, pregnant women, and the elderly.

Polio has been eradicated in a number of countries, and now occurs only in a handful of regions worldwide. Until recently, the last case of non-vaccine related polio in the United States was in 1979. However, in November 2005, four children in an Amish community in Minnesota were diagnosed with polio. None of these children had been vaccinated for polio, which is now a routine measure in the United States.

Besides this small outbreak, there have been very few cases of polio in the Western hemisphere since the late 1970s. This is due to a massive eradication program, which included mass vaccination in these regions. However, there are still areas of the world where polio is widespread. The disease is more common in the summer and fall.

Between 1840 and the 1950s, polio was a worldwide epidemic. Since the development of polio vaccines, the incidence of the disease was greatly reduced. Outbreaks still occur in the developed world, usually in non-immunized groups, often following recent travel to a region where the disease is common. Thanks to a massive global eradication campaign over the past 20 years, as of the end of 2005 polio exists in only four countries: Nigeria, India, Pakistan, and Afghanistan.

There are three basic patterns of polio infection: subclinical infections, nonparalytic, and paralytic. Approximately 95% of infections are subclinical infections, which may go unnoticed.

Clinical poliomyelitis affects the central nervous system (brain and spinal cord), and is divided into nonparalytic and paralytic forms. It may occur after recovery from a subclinical infection.

SUBCLINICAL INFECTION

• No symptoms, or symptoms lasting 72 hours or less
• Slight fever  
• Headache
• General discomfort or uneasiness (malaise)
• Sore throat
• Red throat
• Vomiting

NONPARALYTIC POLIOMYELITIS

• Symptoms last 1 to 2 weeks
• Moderate fever
• Headache
• Vomiting
• Diarrhea
• Excessive tiredness, fatigue  
• Irritability
• Pain or stiffness of the back, arms, legs, abdomen
• Muscle tenderness and spasm in any area of the body
• Neck pain and stiffness
• Pain front part of neck
• Back pain or backache
• Leg pain (calf muscles)
• Skin rash or lesion with pain
• Muscle stiffness

PARALYTIC POLIOMYELITIS

• Fever, occurring 5 to 7 days before other symptoms
• Headache
• Stiff neck and back
• Muscle weakness, asymmetrical (only on one side or worse on one side)
  • Rapid onset
  • Progresses to paralysis
  • Location depends on where the spinal cord is affected
• Abnormal sensations (but not loss of sensation) of an area
• Sensitivity to touch, mild touch may be painful
• Difficulty beginning to urinate
• Constipation
• Bloated feeling of abdomen
• Swallowing difficulty
• Muscle pain
• Muscle contractions or muscle spasms, particularly in the calf, neck, or back
• Drooling
• Breathing difficulty
• Irritability or poor temper control
• Positive Babinski's reflex

Examination may shows signs of meningeal irritation (similar to meningitis), such as stiff neck or back stiffness with difficulty bending the neck. When sitting, the person may need to support the body with their arms.

The person may have difficulty lifting the head or lifting the legs when lying flat on the back. Reflexes may be abnormal. The disorder may resemble encephalitis, and it may affect the cranial nerves and cause difficulty with facial expression, swallowing, chewing, and so on. It may also cause choking or difficulty breathing.

Viral cultures of throat washings, stools, or cerebrospinal fluid (CSF) confirm the diagnosis (see CSF collection). Routine CSF examination may be normal or show slight increase in pressure, protein, and white blood cells. Another way to make the diagnosis is to test for a rise in levels of the antibodies  to the polio virus.

The goal of treatment is to control symptoms while the infection runs its course.

Lifesaving measures, particularly assistance with breathing, may be necessary in severe cases.

Symptoms are treated according to their presence and severity. Antibiotics may be used to treat urinary tract infections. Medications, such as bethanechol, may reduce urinary retention. Pain killers are used to reduce headache, muscle pain, and spasms. Narcotics are not usually given because they increase the risk of breathing difficulty.

Moist heat (heating pads, warm towels, etc.) may reduce muscle pain and spasm.

Activity is limited only by the extent of discomfort and the extent of muscle weakness. Physical therapy, braces or corrective shoes, orthopedic surgery, or similar interventions may eventually be necessary to maximize recovery of muscle strength and function.

The outcome of the disease varies with the form (subclinical, nonparalytic, or paralytic) and the site affected. If the spinal cord and brain are not affected, which is the case more than 90% of the time, complete recovery is likely.

Brain or spinal cord involvement is a medical emergency that may result in paralysis or death (usually from respiratory difficulties).

Disability is more common than death. Infection high in the spinal cord or in the brain are associated with greater risk for respiratory difficulty.

• Spread of infection to other non-immunized persons
• Permanent muscle paralysis, disability, deformity
• Pulmonary edema
• Shock
• Complications of immobility and lung involvement
• Aspiration pneumonia
• High blood pressure
• Urinary tract infections
• Kidney stones
• Paralytic ileus (loss of intestinal functioning)
• Myocarditis
• Cor pulmonale

Call your health care provider if symptoms of poliomyelitis occur.

Call your health care provider if someone close to you has developed poliomyelitis and you are not immunized against the disorder.

Call your health care provider if your child's polio immunization (vaccine) is not up-to-date.

Polio immunization (vaccine) effectively prevents poliomyelitis in most people (immunization is over 90% effective).