This document provides an overview of poliomyelitis (polio). It begins with definitions of polio as a viral infection that can cause paralysis. It describes the three forms of polio infection and discusses transmission through the oral-fecal route. Key points include that there are three poliovirus serotypes, vaccines were developed in the 1950s, and outbreaks still occur in some countries today. The document provides details on symptoms, risk factors, historical information, and the pathogenesis of the poliovirus.

1. POLIOMYELITIS
T. Ramesh
Assistant Professor of Zoology
Vivekananda College
Tiruvedakam

2. CONTENTS
1. What is Polio?
2. Symptoms
3. Vaccine
4. History
5. Causes
6. Risk factors
7. Prevention

3. POLIO
Poliomyelitis
Infectious virus- Genus- Enterovirus
Family- Picornaviridae
Spread easily from person to person
Viral infection that can cause paralysis and death
Destruction of motor neurons in the central nervous
system
Polio infections: Sub-Clinical, Non-Paralytic &
Paralytic

4. SUB CLINICAL FORMS
The most common Polio Infection
Approximately- 95 % of all cases
Asymptomatic and does not Central Nervous System
NON PARALYTIC
Mild symptoms without paralysis
Approximately- 1-5 % of all cases
Affects Central Nervous System

5. PARALYTIC
The most serious cases and rare
 Full or partial Paralysis
Three forms of paralysis
i . Spinal polio- Affects the spinal
ii. Bubar polio- Affects brain stem
iii. Bulbospinal polio- Affects both
Post polio syndrome- Symptoms after 35 years
A TEM micrograph of poliovirus

6. Transmission
 Very Contagious
 Infectious Diseases
 Person-to-Person
 Oral- Fecal Route
 Oral-Oral route
 Poor Sanitation
 Contaminated Water & Food
Incubation period 6 to 20 days
A blockage of the lumbar
anterior spinal cord artery
due to polio (PV3)
Poliomyelitis pathogenesis

7. Reservoirs
 Humans are the only known carrier
 Subclinical- asymptomatic
 Infected do not know that they have the virus and spread it.

8. General Characteristics of Polio
 It is very small- ranges 22 to 33 nm
 Single stranded – apx 7500 nucelotides
 Virus enclosed with icosahedral protein capsid.
 It can survive acid pH environment
 There are three serotypes of poliovirus: namely PV1, PV2 and PV3

9. Key test for Identification
 A stool or pharynx sample from suspected/infected persons
 Cerebrospinal fluid
Signs and Symptoms of
Disease
Non-paralytic : Fever, Sore throat, headache, vomiting, pain in limbs,
stiffness in the neck.
Paralytic: Very similar symptoms like non-paralytic; with in a week
loss of reflexes, severe muscle aches, Weakness, flaccid paralysis-
one side
Post Polio: Muscle or joint weakness and pain; exhaustion after
minimal activity; difficult to breathing; swallowing, intolerance of cold
temeparture; concentration and memory difficulties, depression etc.

10. Historical Information
 1789- Michael Underwood –first record
 1930- three strains were discovered
 1953- Dr. Jonas Salk developed inactivated polio vaccine
 1980- post polio symptoms identified
 1981- Genome sequence
 1999- inactivated polio vaccine replaced by oral polio vaccine

11. Case Reported in 2017
Country Wild cases
Circulating vaccine-
derived cases
Transmission Status Type(s)
Afghanista
n
14 0 endemic WPV1
Pakistan 8 0 endemic WPV1
DRC 0 17 cVDPV only cVDPV2
Syria 0 74 cVDPV only cVDPV2
Total 22 91

12. Virulence factors
 Virus enters- mouth and nose
 Begins replication in the throat and intestines
 Poliovirus use immunoglobulin like a molecules- receptor for recognizing host
cells
 CD155 hosts motor neurons allow virus to attach
 After attached these virus hijacks the cell assembly- cytolysis

13. Thank you