Structure and Characteristics of Polio virus:
1.
Non-enveloped, RNA virus
2.
Replicates in cytoplasm
3.
Single, stranded, Icosahedral nucleocapsid
4.
Acid and bile stable but no long term carrier
state
5.
Three serologic (antigenic) types based on different antigenic determinants on
the outer capsid protein
6.
Release upon death of the cell
 |
| A child suffering from Poliomyelitis |
Disease caused by Polio virus:
Disease cause by polio virus is poliomyelitis
Pathogenesis of Poliomyelitis:
Transmission: faeco-oral route (by ingestion of contaminated food
and drink)
Host: Human
Incubation period: 7-14 days
Mechanism of pathogenesis:
1.
Polio virus enters into the body by faeco-oral
route
2.
Replicate in the lymphoid tissue of the
orophraynx and SI (Peyer’s patches)
3.
Spreads through blood stream to the CNS and also
spreads retrograde along nerve axons
4.
Then replicates in the motor neurons located in
the ant. Horn of the spinal cord
5.
Death of nerve cells
6.
Result: Paralysis of the muscle innervated by
those neurons. Also affects the brain stem, leading to bulbar poliomyelitis
(with respiratory paralysis) but rarely damage the cerebral cortex.
