POLIOMYELITIS

 

POLIOMYELITIS

Poliomyelitis also called infantile paralysis is an acute, highly infectious viral disease of the central nervous system caused by the poliovirus, which mainly affects young children's lower motor neurons of the spinal cord bringing about paralysis, and it is characterized by fever, stiffness in the neck, and pain in the limbs. The incubation period is 7-14 days but it may extend to 25 days. Poliomyelitis is more likely to spread where there is poor sanitation and environmental hygiene as it's mode of transmission is primarily fecal oral route.

Poliomyelitis is caused by the poliovirus. There are 3 main types of polio virus thus:

A, Type I

B.  Type II

C. Type III

Type I poliovirus is the commonest, followed by type III and type II is the list common. The risk factors of poliomyelitis are;

1. Under 5 aged children

2. Immune deficiency

3. Malnutrition

4. Tonsillectomy

4. Lack of immunization against polio then exposure to poliovirus

5. Been in an area that has experienced a polio outbreak.

The nervous system is made up of two parts, the central nervous system (brain and spinal cord), and peripheral nervous system (nerves outside the spinal cord). Sensory neurons transmit electrical messages from the peripherals to the spinal cord and then to the brain for interpretation. This response from the brain is carried by the motor neurons back to the affected peripheral part. In other words sensory neurons they transmit sensations and motor neurons are responsible for movement of the limbs as a response of sensation.

Poliomyelitis is transmitted via fecal oral route. After ingestion of the virus into the G.I.T, some will lodge in the pharynx/throat and some in the intestine. From there, the virus multiply and are disseminated to the lymphoid tissues such as the tonsils. Sustained replication of the virus causes viremia. From the lymphoid tissue, the virus will then be deposited in the bloodstream, where they'll now have access to infect the spinal cord and causes disturbances in the transmission of electrical impulses to the body's muscles resulting in paralysis of the affected muscles.

Basically poliomyelitis may be classified into 3 main types:

1. Subclinical or abortive poliomyelitis. It does not affect the central nervous system.

2. Non paralytic poliomyelitis.

3. Paralytic poliomyelitis. It is further grouped into 3 subtypes;

A. Spinal poliomyelitis

B. Bulbar poliomyelitis

C. Bulbospinal poliomyelitis