This document provides an overview of polio, including: 1. A brief history of polio and its identification and naming. 2. Details on poliovirus itself, including that it is an enterovirus with three serotypes that are targeted by vaccines. 3. The pathogenesis of poliovirus and how it typically enters the body and can in rare cases affect the nervous system and cause paralysis. 4. Epidemiological details on polio including types of infection outcomes and its historic prevalence prior to vaccination efforts. 5. Prevention strategies including the global polio eradication initiative and details on the inactivated and oral polio vaccines used in vaccination programs.

1. POLIO
-by Dr. Sudhir

2. History
 Sir Walter Scott(1771–1832) may have had the
earliest recorded case of polio.
 First described by Michael Underwood in 1789
 Initially thought to be due to trauma
 Became known as the Heine-Medin disease due to
the work of Dr. Jakob Heine and Dr. Karl Oskar
Medin.
 Later called infantile paralysis, based on its
propensity to affect children.
 3rd human disease targeted for eradication

3. Poliovirus
 Enterovirus
 Spherical virion with a single strand
RNA
 Three serotypes: 1, 2, 3
 Burnhilde & Mahoney strains→ type1
 Lansing & MEF-1 → type
2
 Leon & Saukett →type 3
 1 & 3 – epidemic 2 – endemic
Minimal heterotypic immunity between serotypes

4. ANTIGENS
D or Native or N antigen
- whole virion & is type specific
- Anti-D antibody is protective and its conc in
IPV denotes the potency of vaccine
C or Heated or H antigen
- empty non-infectious virus & is less specific
- anti-C antibody does not neutralise infectivity
Heated at 56º C - D →→→ C

5. Resistance
 Resistant to ether, chloroform, bile, intestinal
proteolytic enzymes & detergents
 Stable at pH of 3
 Can survive at -20ºC for yrs, 4ºC for months &
at room temp for 1 day to several weeks
 Inactivated by heat(55ºC for 30 min),
formaldehyde, ultraviolet light & chlorination
 Organic matter in water delays the activation
by chlorination

6. Pathogenesis
 Entry by feco-oral route through ingestion
 Droplets from Patients with early disease
can enter through inhalation or through
conjunctiva
 Replication in the epithelial cells of GI tract
& the local lymphatics

7. Local lymhatics of GIT
↓
Circulatory system (minor or primary viremia)
↓
Reticuloendothelial system
↓
Circulatory system (major or secondary viremia)
↓
Spinal cord & Brain

8. NERVOUS SYSTEM
CNS – Multiplies in Neurons & destroys them
Earliest change – Degeneration of Nissl bodies
Followed by Nuclear changes & finally neuronal
death
Spinal cord – Lesions are mostly in the ant. Horns
causing flaccid paralysis
Post. Horn & intermediate column may also be
involved

9. Outcomes of Poliovirus Infection
90 to 95% polio virus infections are
asymptomatic
Asymptomatic Minor non-CNS illness
Aseptic menigitis Paralytic
0 20 40 60 80 100
Percent

10. Poliovirus Epidemiology
 Reservoir Human
 Transmission Fecal-oral
Oral-oral
possible
 Communicability 7-10 days before or after
onset .
Virus present in stool 3-6
weeks

11. Types
• Asymptomatic Polio
• Non-paralytic
• Paralytic
– Spinal
– Bulbar
– Bulbospinal

12. Asymptomatic Polio
• Accounts for approximately 95% of cases
• Virus stays in intestinal tract and does not
attack the nerves
• Virus is shed in the stool so infected individual
is still able to infect others

13. Non-paralytic Polio
•Abortive poliomyelitis
•Does not lead to paralysis
•Mild symptoms seen such as sore throat, fever, n/v,
diarrhea, constipation ( Minor illness)
•Most recover in <1 week
•Non-paralytic aseptic meningitis ( Major illness)
– Occurs in 1-2% of polio infections
– Symptoms are stiffness in the neck, back, and/or legs
– Increased or abnormal sensations can occur
– Complete recovery after 2-10 days of symptoms

14. Paralytic Polio
Fewer than 1% of those infected develop this
type
Acute flaccid paralysis seen. Initially focal but
spreads over 3 – 4 days
Headache, neck/back stiffness, unusual
sensations, increased sensitivity to touch
Tripod sign +
Descending paralysis
Asymmetrical patchy paralysis
Deep tendon reflex lost before onset of paralysis

15. Spinal Polio
–Most common form of paralytic; 79%
–Attacks motor neurons and causes paralysis of
muscles of respiration and muscles of
extremities
–Children <5 years most likely to become
paralyzed in one leg
–Adults are most commonly paralyzed in both
arms and legs
–Those affected still retain sensation in
extremities

16. Bulbar Polio
• Accounts for 2% of paralytic polio
• Virus attacks motor neurons in brainstem
•Affects cranial nerve function
•Primarily inhibits ability to breathe, speak, and
swallow effectively
Facial asymmetry present

17. Bulbospinal Polio
• Accounts for 19% of paralytic cases
• Affects extremities and cranial nerves
• Leads to severe respiratory involvement

18. Paralytic Polio Risk Factors
• Compromised immune system
• Pregnancy
• Mouth or throat surgery
• Injury or strenuous physical exercise after
exposure to virus

19. Encephalitic Polio
•Very rare
•Causes inflammation of gray matter of brain
•Signs/symptoms include agitation, confusion,
stupor, and coma
•Autonomic dysfunction is common and it has a
high mortality

20. Past Medical Treatment
•Iron Lung - a sealed
chamber with an
electrically driven
bellows that regulates
breathing.
•Rigid Braces
•Body Casts

21. Supportive Treatment
• Antibiotics for infection
• Analgesics for pain
• Portable Ventilators for breathing problem
• Moderate Exercise
• Nutritional Diet

22. Post-Polio syndrome (PPS)
25 % of individuals, decades after recovering
from the acute infection
Features include muscle weakness, extreme
fatigue, or paralysis.
Due to failure of the over-sized motor units
created during recovery from paralytic disease
Factors that increase the risk of PPS include
time since acute poliovirus
infection,permanent residual impairment, and
both overuse and disuse of neurons

23. PREVENTION

24. Global Polio Eradication Initiative launched in
1988
Polio cases have decreased by over 99% since
1988, from an estimated 350 000 cases then, to
1604 reported cases in 2009.
In 2010, only four countries in the world remain
polio-endemic, down from more than 125 in 1988.
The remaining countries are Afghanistan, India,
Nigeria and Pakistan

25. Wild Poliovirus 1988

26. Wild Poliovirus 2002

27. Wild Poliovirus 2012

28. Wild Poliovirus 2014

29. Core strategies of GPEI
1. High infant immunization coverage with four
doses of oral poliovirus vaccine (OPV) in the
first year of life
2. Supplementary doses of OPV to all children
under five years of age during SIAs(PPI)
3.AFP surveillance among children under fifteen
years of age;
4. Targeted “mop-up” campaigns once wild
poliovirus transmission is limited to a specific
focal area.

30. Poliovirus Vaccine
 1955 Inactivated vaccine
 1961 Types 1 and 2 monovalent OPV
 1962 Type 3 monovalent OPV
 1963 Trivalent OPV
 1987 Enhanced-potency IPV (IPV)

31. Inactivated Polio Vaccine
 Developed in 1952 by Jonas Salk
 Contains 3 serotypes of vaccine virus
 40 units of 1(Mahoney), 8 units of 2(MEF-1) &
32 units of 3(Saukett)
 Grown on monkey kidney (Vero) cells
 Inactivated with formaldehyde
 Contains trace 2-phenoxyethanol, neomycin,
streptomycin, polymyxin B
 Safe in immunocompromised & in pregnancy

32. Inactivated Polio Vaccine
 Heat stable at room temp but should be
refrigerated to preserve potency
 Highly effective in producing immunity to
poliovirus
 >90% immune after 2 doses
 >99% immune after 3 doses
 Humoral immunity and to some extend
pharyngeal immunity
 Duration of immunity not known with
certainty

33. Oral Polio Vaccine
 Discovered by Albert Sabin
 Contains 3 serotypes of vaccine virus
3 lakh TCID 50 of type 1
1 lakh TCID 50 of type 2
3 lakh TCID 50 of type 3
 Grown on monkey kidney (Vero) cells
 Contains neomycin and streptomycin
 Shed in stool for up to 6 weeks following
vaccination

34. Oral Polio Vaccine
 Produces both Humoral & local immunity
 Contributes to herd immunity
 50% immune after 1 dose
 >95% immune after 3 doses
 Immunity probably lifelong
 Heat labile: -20ºC
 Can be stabilised by adding MgCl
 Should not be frozen & thawed repeatedly

35. Polio Vaccine Adverse Reactions
 Rare local reactions (IPV)
 No serious reactions to IPV have been
documented
 Paralytic poliomyelitis (OPV)

36. Polio Vaccine
Contraindications and Precautions
 Severe allergic reaction to a vaccine
component or following a prior dose of
vaccine
 Moderate or severe acute illness

37. Vaccine-Associated Paralytic Polio
 Mutation of the vaccine inside the body may
case lose of attenuation(itself brought on by
reversion) leads to paralytic polio
 Increased risk in persons >18 years &
those with immunodeficiency ( B cell)
 No procedure available for identifying
persons at risk of paralytic disease
 5-10 cases per year with exclusive use
of OPV

38. 2005 in India: Wild case: 66; VAPP 180
Many countries switched to sequential IPV-OPV
and then only IPV schedules once the number
of VAPP cases exceeded wild polio cases.

39. Vaccine-Derived Paralytic Polio
virus
These viruses like those causing VAPP are
neurovirulent but additionally are transmissible
and capable of causing outbreaks.
They have been classified into three groups;
circulating VDPV (cVDPV), VDPV in the
immuno-deficient (iVDPV) and VDPV of
ambiguous origin (aVDPV).
Risk factors for outbreaks due to cVDPV include
dropping immunization coverage (both routine
and SIA's), high population densities, tropical
conditions and previous eradication of wild virus

40. POLIO & ITS PREVENTION IN INDIA

41. India is one of the four countries with wild polio
virus
Most cases are reported from Bihar & UP
Cases seen in various states of north india are
due to import from there 2 states
2010 – 42 cases
Last case of type 2 in 1999
Last WPV3 Oct 2010
Last WPV1 Jan 2011
Polio free country – Jan 2014

42. Polio Vaccination under UIP
Vaccine
OPVº
OPV1
OPV2
OPV3
OPV4
Age
birth
6 wks
10 wks
14 wks
16-24 Months

43. Two drops of OPV is used
Nose should not be pinched
Instead apply pressure to both side of mouth
Breast feeding is not contraindicated
Hot liquids to be avoided for ½ hr after OPV

44. Pulse Polio Immunization (PPI)
The supplementary
immunization activities
(SIAs) in India launched in
1995
Irrespective of the
immunisation status
Usually Dec & Jan – Peak
transmission

45. Providing additional OPV doses to every child aged <5
years at intervals of 4-6 weeks during National
Immunization Days (NIDs) & sub-National
Immunization Days (SNID's)
It “Flood” the community with OPV within a very short
period of time, thereby interrupting transmission of
virus throughout the community.
Intensification - house-to-house “search and vaccinate”
component.
The number of PPI rounds is determined by the extent
of poliovirus transmission in the country.

46. Cold Chain
The system of transporting, storing and
distributing vaccine in a potent state at
recommended temperature till it is
administered to an individual.
If cold chain is not maintained from the
manufacturer to the place of vaccination, the
vaccine efficacy greatly suffers
Most vaccines lose their potency by heat and
sunlight and hence need protection from
both(2).

47. The Cold Chain Equipment
(a) Walk in cold rooms: 3 months and serve districts.
(b) Deep freezers (300 ltr) and Ice lined Refrigerators: Deep
freezers are used for making ice packs and to store OPV
and measles vaccines.
(c) Small deep freezers and ILR (140 ltr)
(d) Cold boxes: peripheral centers.mainly for transportation.
(e) Vaccine carriers:Used to carry small quantities of
vaccines (16-20 vials) for the out of reach sessions.
(f) Ice packs

48. Vaccine Vial Monitoring
The vaccine vial monitor is a small
thermochromic sticker on the vaccine vial
and changes color as the vaccine is
exposed to heat.
The color of the sticker tells whether the
vaccine must be discarded due to excessive
heat exposure.
It reduces uncertainty and waste.

50. AFP Survillance
Acute flaccid paralysis is defined as:
Any case of AFP in a child aged <15 years, or any
case of paralytic illness in a person of any age
when polio is suspected.
All health facilities, clinicians and other
practitioners are required to notify AFP cases
immediately to the DIO, by the fastest means
available

51. Sample Collection
Two stool specimens are collected as soon as
possible after the onset of paralysis in the child
– ideally within 14 days of onset of paralysis
and at least 24 hours apart. Specimens
collected within 14 days are much more likely
to yield the virus.
Each specimen should be 8 grams – each
about the size of one adult thumb – collected
in a clean, dry, screw-capped container. The
container need not be sterile and no
preservative/transport media should be used.

52. Reverse Cold Chain
The specimens are transported in the “cold chain” – on
frozen ice packs or ice, in a stool specimen carrier or a
vaccine carrier specifically designated for this purpose
– to one of India’s eight WHO-accredited polio
laboratories.
Indicator of the quality of the “reverse cold chain”
↓
% of Stool specimens from which a non-polio
enterovirus is isolated→ ≥10
(i.e. that the specimen has been continuously
maintained at temperatures <8° C during
transportation from the field to the laboratory)

53. 60-day follow-up examination:
To confirm the presence or absence of residual
weakness. A 60-day follow-up exam if
1) inadequate or no stool specimens
2) isolation of vaccine virus from the stool
3) isolation of wild poliovirus from the stool
4) strongly suggestive of poliomyelitis on initial
examination (“hot case”).
The child is assessed for weakness, asymmetrical skin
folds, and difference in left/right mid-arm/mid-thigh
circumference. The child is considered to have residual
weakness if any of the above is present, even if
minimal. The finding of residual weakness taken into
account during final case classification

54. Classification

55. Outbreak response immunization
(ORI)
House-to-house immunization following the AFP
case investigation and stool specimen collection
Children aged 0-59 months are given one dose of
oral poliovirus vaccine (OPV) regardless of the
number of doses received previously. The
recipients include children of the target age
group in the village/locality of the AFP case.
The investigation team searches for additional
AFP cases in the community, which – if present
– could signal the possibility of a polio outbreak.

56. Active case search
Where an AFP case resides – or where an AFP
case has visited during the incubation period
for polio (4-25 days before paralysis onset)
Carried out immediately along with ORI.
A search is conducted for any children aged <15
years who have had the onset of flaccid
paralysis within the preceding 60 days. All
cases that are found are investigated
immediately, with collection of two stool
specimens before administration of OPV.

57. “Mopping-up” immunization
Started when poliovirus transmission has been
reduced to well-defined and focal geographic
areas.
Intensive house-to-house, child-to-child
immunization campaigns are conducted over a
period of days to break the final chains of virus
transmission.

58. THANK YOU