Poliomyelitis

Poliomyelitis

Instructional Objectives:At the end of the lecture the student would be able to:1-Demonstrate the main clinical characteristics of poliomyelitis.2-Point out the occurrence of the disease.3-List the causative agent, mode of transmission, incubation period, and period of communicability of poliomyelitis.4-List the main preventive measures of poliomyelitis.5-Describe the control measures of poliomyelitis.6-Define the WHO strategies of polio eradication.

Polio virus infection occur in GI tract

with spread to regional LN and in
minority of cases to CNS

Flaccid paralysis occurs in <1 % of polio virus

infection

>90% of infections are either in apparent or

non specific fever


Aseptic meningitis occurs in about 1%
of infections
Clinical responses are extremely varied

In apparent: Paralytic polio=200:1

Minor illness: Manifested as low grade fever, malaise, headache, nausea & vomiting (10%)


major illness: Manifested as Sever muscle spasm, followed by Neck & back stiffness, it ends with flaccid paralysis:
Asymmetrical
Maximized within 3-4 days
Site is depend on the location of nerve cell destruction in the spinal cord or brain stem
Legs are affected more than arms
Proximal parts more often than distal parts

Affected muscles are floppy, reflexes are diminished ,sense of pain & touch remain normal
Residual paralysis is usually present after 60 days
Severe cases : quadriplegia , abdomen & thoracic muscles , bulbar polio

Differential diagnosis of Acute flaccid paralysis (AFP):

Paralytic polio
Guillian Barre syndrome
Transverse myelititis
Traumatic neuritis
Acute motor axonal neuropathy
Encephalitis
Meningitis
Tumors

Distinguishing characteristics:

Asymmetrical flaccid paralysis
Fever at onset
Rapid progression of paralysis
Residual paralysis after 60 days
Preservation of sensory nerve function

Causative agent :

Entero virus :
Type 1 2 & 3
Paralytogenic less commonly
Most frequent frequent cause
Cause of outbreak of vaccine
associated.


Occurrence :
Prior to immunization it had a world wide distribution.
It is eradicated from the western Hemispheres & industrialized countries
The greatest risk of polio now occurs on the Indian sub continent ,&to lesser extent , in the countries of west &central Africa
If cases appeared in industrialized countries they are either imported or vaccine associated

High risk groups:

Groups that refused immunization
Minority population
Migrants
Unregistered children
Refuges & poor urban
Age of distribution:
Remains primarily a disease of infants & young children ,in many polio endemic regions 70-80% of cases are <3 years of age & 80-90% are <5 years of age

Seasonality :

hot , rainy ,season tropical
Late summer & autumn temperate

Reservoir :

Human most frequently persons with in apparent infections .
Long term carriers have not been found.


Mode of transmission:
Direct person to person principally through fecal –oral transmission
- bad standard of sanitation
- young children
Pharyngeal droplets
- good sanitation
- older age groups
Food , milk, & other materials contaminated with feces rare
Insects no reliable evidence exists
Water ,sewage , rarely implicated .

Incubation period:

7- 14 days for paralytic cases
Reported range of 3-35 days

Period of communicability:

Not precisely defined
Transmission is possible as long as the virus is excreted
Virus appeared in throat secretion as early as 36 hrs & in feces 72 hrs after exposure to infection
Virus persists in the throat for (1) week &in the feces for 3-6 weeks


Prevention:
Education of public on the advantages of immunization in early childhood
Vaccination trivalent (OPV)
inactivated (IPV)

OPV:

Advantages:
Recommended by WHO for polio eradication &EPI
3 doses will protect at least 80-85 % of immunized children
Induces both circulating antibody &intestinal resistance.
Immunize some susceptible contacts through secondary spread
Low cost, (however)

OPV:

Disadvantages:
Low rates of seroconversion in developing countries

It is contra indicated in all immune deficient persons

Vaccine associated paralysis (VAPP) 1:2.5,000,000 doses (1:800000 in 1st dose)
Lower level of serum antibodies (break down in the cold chain, acute diarrhea, or local intestinal immunity)

Reading the vaccine vial monitor ((VVM))

IPV:

Prevents paralytic polio by producing sufficient Antibodies In the serum
It has no risk of vaccine associated paralysis
Lower level of intestinal immunity
More expensive.

Vaccine Schedule

Birth zero dose
6 wks 1st dose
10 wks 2nd dose 4 basic doses
14 wks 3rd dose of OPV
9 months for children not immunized at birth
If OPV is given to child with diarrhea the dose should be repeated


The recommended schedule of immunization in Iraq
• root
• vaccines
• age
• ID+ORAL+IM
• B.C.G+POLIO(0)+HB1
• 1 week
• IM+ORAL+IM
• D.P.T(1)+POLIO(1)+HB2
• 2 Months
• IM+ORAL
• D.P.T(2)+POLIO(2)
• 4 Months
• IM+ORAL+IM
• D.P.T(3)+POLIO(3)+HB3
• 6 Months
• SC+ORAL
• MEASLES+VIT A
• 9 Months
• SC
• M.M.R
• 15Months
• ORAL+IM
• FIRST.B00STER POLIO+D.P.T
• 18-24 Months
• ORAL+IM
• 2nd..B00STER POLIO+D.P.T
• 4-6 Years


Control:
Reporting is obligatory any case of AFP under 15 y should be fully investigated (clinical, epidemiological, and stool culture)
Isolation
Concurrent disinfection
Protection of contacts
Inv of source
No Sp Rx

Polio Eradication :

Polio is one of only a limited number of diseases they can be eradicated

Polio only affects human

An effective vaccine is available
Immunity is life long
No long term carriers
No animal or insect reservoir
Virus can only survive for a very short period in the environment

Strategy of Eradication:

High routine immunization coverage with OPV i.e giving the 4 basic doses during the 1st year of life
Supplementary immunization in the form of mass campaigns or NIDs
Effective surveillance.
Final stage when Very few or no cases are occurring ,door-to-door immunization campaigns (mopping up) in areas where the virus persists.


Number of confirmed Polio cases in the EMRO Region 2009-2010-2011

• Date of last case

• 2011
• 2010
• 2009
• Country
• 20/04/2011
• 38
• 144
• 89
• Pakistan
• 11/01/2010
• 1
• 25
• 38
• Afghanistan
• 40
• South Sudan
• 5
• North Sudan
• 20/04/2011
• 39
• 169
• 172
• Total