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 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 childrenPharyngeal droplets - good sanitation - older age groupsFood , milk, & other materials contaminated with feces rareInsects no reliable evidence existsWater ,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.
The recommended schedule of immunization in Iraq
rootvaccines
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
The new recommended schedule of immunization in Iraq 2016
RoutVaccines
Age
ID+ORAL+IM
B.C.G+ OPV(0) +HB1
1st 24 hours
IM+ORAL+ORAL+IM
HEXA(1)+ OPV(1) +Rota(1)+PREV13(1)
2 Months
IM+ORAL+ORAL+IM
HEXA(2)+ OPV(2) +Rota(2)+PREV13(2)
4 Months
IM+ORAL+ORAL+IM
HEXA(3)+ OPV(3) +Rota(3)+PREV13(3)
6 Months
SC+ORAL
MEASLES+VIT A(100000IU)
9 Months
SC
M.M.R
15Months
IM+ORAL+ORAL
PENTA+ OPV +VIT. A (20000IU) PENTA(DPT+HiB+IPV)
18-24 Months (First Booster)
IM+ORAL+ORAL+SC
TETRA+ OPV +VIT. A (20000IU)+MMR TETRA-(DTaP+IPV)
4-6 Years (Second Booster)
HEXA-(DTP+Hib+HB+IPV) PENTA-(DPT+HiB+IPV) TETRA-(DTaP+IPV)
The new recommended schedule of immunization in Iraq 2016
Changes in National schedule in regard to Polio (2016): 1- Introduction of IPV to the schedule 2- Switching the use of Trivalent OPV (1,2,3) to Bivalent (1,3) OPVControl:
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 RxPolio 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.