polio

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

The majority of polio infections are asymptomatic. In about 1% of cases the virus enters the central nervous system (CNS) via the blood stream.

Within the CNS, poliovirus preferentially infects and destroys motor neurons.

The destruction of motor neurons causes muscle weakness and flaccid paralysis.

Paralytic polio

In approximately 1 in 100 to 1 in 1000 cases poliovirus infection leads to paralytic disease, in which patients develop flaccid paralysis.

Depending on the site of paralysis, poliomyelitis can be classified as spinal, bulbar, or spino-bulbar.

Up to 0.2% of all polio infections (but nearly 20% of paralytic polio cases) require mechanical ventilation of the patient during the acute stage, and permanent quadriplegia or respiratory paralysis occur in only 0.01% (1 in 10,000) of all poliovirus infections.

Spinal polio

The location of motor neurons in the anterior horn cells of the spinal column.

The poliovirus affects the motor neurons of the anterior horn cells, or the ventral (front) grey matter section in the spinal column, which control movement of the trunk and limb muscles including the intercostal muscles.[23] The color and appearance of the grey matter of the spinal cord are often altered by polio infection, appearing reddish and swollen due to extensive inflammation, caused by replication of polio virus within the motor neurons of the anterior horn and brain stem. This inflammation results in damage or destruction of motor neuron ganglion within the grey matter; causing the typical clinical symptoms of poliomyelitis.[23]

Bulbar polio

The location and anatomy of the bulbar region (in orange).

Bulbar polio and spinal polio are part of a continuum of anatomy and disease (paralytic polio). Bulbar polio occurs in 2% of cases of paralytic polio, and describes the form of the disease which affects the bulbar region of the brain stem.

Diagnosis Polio is a rare disease in much of the world, and

few doctors have ever seen a case of polio. If polio is suspected, however, the usual follow-up test is a lumbar puncture, or "spinal tap", to collect the patient's cerebrospinal fluid (CSF). The CSF of individuals with polio contains an increased number of white blood cells (primarily lymphocytes) and a mildly elevated protein level.[27]

When poliovirus is isolated from a patient experiencing acute flaccid paralysis, it is then further tested, using oligonucleotide mapping (genetic fingerprinting), or more recently by by PCR amplification, to determine if the virus is “wild type” (that is, the virus encountered in nature) or vaccine type (is derived from a strain of poliovirus used to produce polio vaccine).

Isolation of wild poliovirus constitutes a public health emergency, and appropriate control efforts must be initiated immediately.

Treatment

The iron lung Antibody serum Vaccine Salk's "inactivated polio vaccine" Sabin's "oral polio vaccine"