Poliomyelitis

Poliomyelitis, often called infantile paralysis, is an acute viral infectious disease spread from person to person, primarily via the fecal-oral route.

1. The term derives from the Greek poliós (πολιός), meaning "grey", myelós (µυελός), referring to the "spinal cord", and the suffix -itis, which denotes inflammation.

2. Although around 90% of polio infections cause no symptoms at all, affected individuals can exhibit a range of symptoms if the virus enters the blood stream.

3. In about 1% of cases the virus enters the central nervous system, preferentially infecting and destroying motor neurons, leading to muscle weakness and acute flaccid paralysis. Different types of paralysis may occur, depending on the nerves involved.

Spinal polio is the most common form, characterized by asymmetric paralysis that most often involves the legs.

Bulbar polio leads to weakness of muscles innervated by cranial nerves. Bulbospinal polio is a combination of bulbar and spinal paralysis.

Poliomyelitis, infectious viral disease that sometimes results in paralysis. The infection chiefly affects children and young adults and is caused by any one of three related viruses called polioviruses.

In more than 95 percent of cases, the infection may pass without creating severe or even noticeable illness because the body’s immune system neutralizes the invading virus and protects against future infection.

In a small percentage of cases the virus penetrates to the central nervous system, infecting cells that control muscle function. Such infection can result in permanent paralysis of limbs. In its most perilous form, the infection attacks the brain, creating complications that sometimes result in death.

The term poliomyelitis derives from Greek words referring to inflammation (itis) of the gray (polios) matter of the spinal cord (myelos). The shortened term polio is commonly used by the public and medical professionals, and the disease has also been referred to as infantile paralysis.