Poliomyelitis
Dr Amol Koshti MD (Ay)
Asso. Professor
Poliomyelitis
An acute viral infection caused by RNA virus
It is primarily an infection of alimentary tract
But may infect nervous system resulting in
varying degree of paralysis and possibly death
Rainy season, overcrowding,
poor sanitation play important
role in transmission
Environmental
factors
Agent factors Host factors
AGENT – RNA virus – serotype -1,2 AGE– all ages, more in children of
&3 age 6 months – 3yr
SEX – 3 Male : 1 Female
RESERVOIR OF INFECTION – RISK FACTORS – fatigue, trauma,
Human (case & subclinical case) IM injections, operative procedures
INFECTIVE MATERIAL – faeces, such as tonsillectomy,
oropharyngeal secretions administration of DPT vaccine
INFECTIVITY – IMMUNITY – maternal antibodies
7-10 days before and after onset of disappear during 1st 6 months of
symptoms life
Immunity after infection is good
Mode of Transmission – faecal-oral route,
droplet infection
Incubation period – 7-14 days
Clinical spectrum
Inapparent infection
91-96% of cases – no presenting symptoms
Recognized by virus isolation or rising antibody titre
Abortive polio or minor illness
In 4-8% of cases – mild, self limiting illness
Recognized by virus isolation or rising antibody titre
Non-paralytic polio
Occurs in 1% of cases – stiffness & pain in neck & back
Disease lasts for 2-10 days – recovery is rapid
Paralytic polio
Occurs in less than 1% of cases
Virus invades in CNS – causes paralysis
Paralysis is characterized as descending – starting at hip then moves down
Treatment
NO treatment
Prevention
IPV – Inactivated polio vaccine
(Salk)
OPV – Oral polio vaccine (Sabin)
Inactivated polio vaccine Oral polio vaccine
Doses – Primary 4 doses – Doses –
First 3 doses are given at First dose at birth with
the interval of 1-2 months BCG
First dose at age of 6 Then at 6th, 10th and
weeks 14th week of age
4th dose 6-12 months Booster dose – 12-18
after 3rd dose months of age
Additional dose prior to
school entry and then
every 5 years upto age of
18 yr
Differences between IPV & OPV
IPV (Salk type) OPV (Sabin type)
Killed vaccine Live attenuated vaccine
Given IM or subcutaneously Given orally
Induces humoral immunity but Induces both humoral &
no intestinal immunity intestinal immunity, induces
Prevents paralysis but does antibodies quickly
not prevent intestinal re- Prevents both paralysis and
infection
intestinal re-infection
Not useful in controlling
epidemics
Effective in controlling
More difficult to manufacture epidemics
Costlier
Easy to manufacture
Does not require stringent Cheaper
conditions during storage and Require to be stored and
transportation. Has longer transported at subzero
shelf - life temperatures
Pulse polio immunization
Will be discussed in details in the class
of Polio control programme
Thank
