مكتب الجامعة للطباعة والاستنساخ
طب مجتمع \د.زيد شندالة \محاضرة 8عدد الاوراق :4
السعر :250
مكتب الجامعة للطباعة والاستنساخ
طب مجتمع \د.زيد شندالة \محاضرة 8
عدد الاوراق :4
السعر :250
Poliomyelitis
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 feverAseptic 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
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
If cases appeared in industrialized countries they are either imported or vaccine associated
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
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 casesReported 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)
IPV:
Prevents paralytic polio by producing sufficient Antibodies In the serumIt has no risk of vaccine associated paralysis
Lower level of intestinal immunity
More expensive.
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 lifeSupplementary 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.