Despite polio's ability to cause paralysis and death, the vast majority of people who get the poliovirus don't become sick and are never aware they've been infected with polio. Yet even without signs or symptoms of polio, they still shed the virus intermittently in their stool for several weeks and occasionally for months. In areas with poor sanitation, a single person with poliovirus can potentially infect hundreds of others before the first case of polio that causes paralysis appears.
Nonparalytic Polio
A small number of people who contract poliovirus develop nonparalytic polio a type of polio that doesn't lead to paralysis (abortive poliomyelitis). This usually causes the same mild, flu-like signs and symptoms sore throat, fever, nausea, vomiting, and constipation or diarrhea typical of other viral illnesses. Most people recover from abortive polio in less than a week.
About 5 percent to 10 percent of infected people develop nonparalytic aseptic meningitis, a viral infection of the outer covering (meninges) of the brain. Signs and symptoms, which generally last two to 10 days, include:
- Fever
- Headache
- Vomiting
- Diarrhea
- Fatigue
- Back pain or stiffness
- Neck pain or stiffness
- Pain or stiffness in the arms or legs
- Muscle spasms or tenderness
Paralytic Polio
Fewer than 1 percent of people infected with poliovirus develop paralytic polio, the most serious form of the disease. Paralytic polio often begins with a fever. Five to seven days later, other signs and symptoms appear, including :
- Headache
- Neck and back stiffness
- Constipation
- Increased sensitivity to touch
The paralytic polio symptom that causes limbs to appear loose and floppy (acute flaccid paralysis) often comes on suddenly and usually is worse on one side of the body.
Paralytic polio has historically been divided into several types, depending primarily on which part of the body is affected. These classifications aren't rigid, and overlap may occur among the different forms. In the past, distinctions among polio types may have varied with the method and time of diagnosis.
- Spinal polio. This most common form of paralytic polio attacks certain nerve cells (motor neurons) in your spinal cord and may cause paralysis of the muscles that control breathing and those in your arms and legs. The muscles affected and the extent of paralysis depend on the part of the spinal cord and number of neurons involved. Although paralysis can occur in any combination of limbs for instance, both legs and one arm children under age 5 are most likely to become paralyzed in a single extremity, while in adults, paralysis of both arms and legs is more common.
Sometimes the neurons are only damaged, in which case you may recover some degree of muscle function. But if the neurons are completely destroyed, the paralysis is irreversible, although you still retain your sense of feeling, unlike after many spinal cord injuries.
- Bulbar polio. In this severe type of polio, the virus affects the motor neurons in your brainstem, where the centers of the cranial nerves are located. These nerves are involved in your ability to see, hear, smell, taste and swallow. They also affect the movement of muscles in your face and send signals to your heart, intestines and lungs. Bulbar polio can interfere with any of these functions but is especially likely to affect your ability to breathe, speak and swallow and can be fatal without respiratory support.
- Bulbospinal polio. A combination of both bulbar and spinal paralytic polio, this form can lead to paralysis of your arms and legs and may also affect breathing, swallowing and heart function.
Post-Polio Syndrome
Affecting some people who have recovered from polio, post-polio syndrome is a cluster of disabling signs and symptoms that appears decades between 10 and 40 years after the initial illness. Common signs and symptoms include :
- New muscle weakness in limbs that may or may not have been affected initially
- General fatigue and exhaustion after minimal activity
- Muscle and joint pain
- Breathing or swallowing problems
- Sleep-related breathing disorders, such as sleep apnea
- Decreased tolerance of cold temperatures
The above information thankfully comes from the Mayo Clinic.com at the following link.