Causes, incidence, and risk factors

Poliomyelitis is a disease caused by infection with the poliovirus. The virus spreads by:

• Direct person-to-person contact

• Contact with infected mucus or phlegm from the nose or mouth

• 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. The time from being infected with the virus to developing symptoms of disease (incubation) ranges from 5 - 35 days (average 7 - 14 days).

Risks include:

• Lack of immunization against polio

• Travel to an area that has experienced a polio outbreak

In areas where there is an outbreak, those most likely to get the disease include children, pregnant women, and the elderly. 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 has been greatly reduced. Polio has been wiped out in a number of countries. There have been very few cases of polio in the Western hemisphere since the late 1970s. Children in the United States are now routinely vaccinated against the disease.

Outbreaks still occur in the developed world, usually in groups of people who have not been vaccinated. Polio often occurs after someone travels to a region where the disease is common. As a result of a massive, global vaccination campaign over the past 20 years, polio exists only in a few countries in Africa and Asia.

Symptoms

There are three basic patterns of polio infection: subclinical infections, nonparalytic, and paralytic. About 95% of infections are subclinical infections, which may not have symptoms.

SUBCLINICAL INFECTION SYMPTOMS

• General discomfort or uneasiness (malaise)

• Headache

• Red throat

• Slight fever

• Sore throat

• Vomiting

People with subclinical polio infection might not have symptoms, or their symptoms may last 72 hours or less.

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.

NONPARALYTIC POLIOMYELITIS

• Back pain or backache

• Diarrhea

• Excessive tiredness, fatigue

• Headache

• Irritability

• Leg pain (calf muscles)

• Moderate fever

• Muscle stiffness

• Muscle tenderness and spasm in any area of the body

• Neck pain and stiffness

• Pain in front part of neck

• Pain or stiffness of the back, arms, legs, abdomen

• Skin rash or lesion with pain

• Vomiting

Symptoms usually last 1 - 2 weeks.

PARALYTIC POLIOMYELITIS

• Fever 5 - 7 days before other symptoms

• Abnormal sensations (but not loss of sensation) in an area

• Bloated feeling in abdomen

• Breathing difficulty

• Constipation

• Difficulty beginning to urinate

• Drooling

• Headache

• Irritability or poor temper control

• Muscle contractions or muscle spasms in the calf, neck, or back

• Muscle pain

• Muscle weakness that is only on one side or worse on one side

  • Comes on quickly

  • Location depends on where the spinal cord is affected

  • Worsens into paralysis

• Sensitivity to touch; mild touch may be painful

• Stiff neck and back

• Swallowing difficulty

Signs and tests

The health care provider may find:

• Abnormal reflexes

• Back stiffness

• Difficulty lifting the head or legs when lying flat on the back

• Stiff neck

• Trouble bending the neck

Tests include:

• Cultures of throat washings, stools, or cerebrospinal fluid (CSF)

• Routine CSF examination

• Test for levels of antibodies to the polio virus

Treatment

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

People with severe cases may need lifesaving measures, especially breathing help.

Symptoms are treated based on their severity. Treatment may include:

• Antibiotics for urinary tract infections

• Medications (such as bethanechol) for urinary retention

• Moist heat (heating pads, warm towels) to reduce muscle pain and spasms

• Painkillers to reduce headache, muscle pain, and spasms (narcotics are not usually given because they increase the risk of breathing trouble)

• Physical therapy, braces or corrective shoes, or orthopedic surgery to help recover muscle strength and function

Expectations (prognosis)

The outlook depends on the form of the disease (subclinical, nonparalytic, or paralytic) and the body area affected. If the spinal cord and brain are not involved, 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 problems).

Disability is more common than death. Infection that is located high in the spinal cord or in the brain increases the risk of breathing problems.

Complications

• Aspiration pneumonia

• Cor pulmonale (a form of heart failure found on the right side of the circulation system)

• High blood pressure

• Kidney stones

• Lack of movement

• Lung problems

• Myocarditis

• Paralytic ileus (loss of intestinal function)

• Permanent muscle paralysis, disability, deformity

• Pulmonary edema

• Shock

• Urinary tract infections

Post-polio syndrome is a complication that develops in some patients, usually 30 or more years after they are first infected. Muscles that were already weak may get weaker. Weakness may also develop in muscles that were not affected before.

Calling your health care provider

Call your health care provider if:

• Someone close to you has developed poliomyelitis and you haven't been vaccinated

• You develop symptoms of poliomyelitis

• Your child's polio immunization (vaccine) is not up to date

Prevention

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