Poliomylitis Dr. Abbas Etiology - PowerPoint Presentation

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Poliomylitis

Dr.

Abbas

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Etiology

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Epidemiology

Paralysis is the most devastating effect of polio virus infection

Although 90-95 % infection-subclinical

Eradicated in most of countries except Nigeria, Afghanistan and Pakistan

Universal vaccination strategy and improved sanitation: key factor in eradication

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Transmission

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Pathogenesis

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Pathogenesis(contd..)

Vaccine strain of polio do not replicate in CNS.

Occasional

revertants

(by nucleoside

subtitution

) of these vaccine strain developed a

neurovirulent

phenotype and cause Vaccine acquired paralytic

poliomylitis

Reversion occur in small intestine and reaches to CNS via. Peripheral nerves

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Infection

Traverse neural pathways and multiple site within CNS

Perineural inflammation and destruction

Petachial hemorrhages and inflammatory edema

Primarily infect motor neuron in anterior horn cells and medulla oblongata(cranial nerve nuclei)

Involvement of reticular formation that controlled vitals may have catastrophic out come

Pathogenesis(contd..)

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Involvement of dorsal horn and dorsal root

ganglias

of spinal cord results in hyperesthesia and

myalgias:typical

of acute

polimyelitis

Other neuron affected are the

nuclie

in the

vermis

of cerebellum,

substantia

nigra,thatmus,hypothalmus

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Clinical features

I.P- 8-12 days ,ranges from 5- 35 days

Infection with wild polio virus may follow several courses

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Abortive poliomyelitis

Non specific flu like illness.

phgysical

examination

: non specific pharyngitis, abdominal or muscular tenderness and weakness

Recovery : complete without sequelae

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Non- Paralytic poliomyelitis

Sign of abortive poliomyelitis but more intense

Headache, nausea, vomiting , sore throat, neck & spinal rigidity, fleeting paralysis of bladder and constipation.

Changes in Reflexes may precede before onset of paralysis

.

Superficial reflexes, cremastric, abdominal and reflexes of ,spinal, gluteal muscle.

Spinal and gluteal reflexes disappear before other reflexes

.

Changes in DTR occur after 8-24 hrs after superficial reflexes diminished.DTR are absent with paralysisSensory defect don’t occur in poliomyelitis

Recovery : complete

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Paralytic poliomyelitis

Spinal

Bulbar

Encephalitis

Paralysis

Appears 3-8days after the initial symptoms

Clinical features of paralytic polio caused by wild or vaccine strain are comparable

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Spinal paralytic polio

ist phase

Symptoms similar to abortive polio

Patient appear to feel better for 2-5 days

Biphasic disease

Severe headache and fever and exacerbation of previous symptoms.

Severe muscle pain sensory and motor phenomenon.

Physical examination: distribution of paralysis characteristically spotty

After 1-2 days asymmetric flaccid paralysis occur

Involvement of 1 leg is most common , followed by involvement of 1 leg and 1 arm

Proximal areas of the extremities tend to be involved to a greater extent.

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Polio Paralysis

Some times biphasic phase absent.

50-60% cases h/o IM injection before paralysis(provocation paralysis)

Paralysis start .

Little recovery from paralysis noticed during ist few days but not beyond 6 months.

Return of strength and reflexes is slow and & may continue to improve as long as 18 months after the acute

ds

.

Atrophy of limb ,growth failure and deformity finally evident

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Bulbar Polio

Dysfunction of cranial nerve and medullary centers without involving spinal cord

Respiratory difficulty, paralysis of extraoccular, facial and masticatory muscles.

1-nasal twang to the voice or cry.

2-inability swallow smoothly ,

3-absence of effective coughing

4-nasal regurgitation of saliva

5-deviation of palate, uvula, tongue

6-involvement of vitals centre in the medulla

7-paralysis of 1 or both vocal cords

8- Rope sign

: acute angulations b/w chin and larynx caused by weakness of hyoid muscle

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Polioencephalitis

Rare form of disease

Higher centre of brain severely involved

Seizure, coma ,spastic paralysis, irritability, disorientation, drowsinesss,cranial nerve paralysis, deaths

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Diagnosis

Paralysis in any unimmunized or partially immunized children

VAPP should be considered in any child with paralysis developed 7-14 days after receiving OPV.

Combination of fever ,headache, neck and back pain,assymmetric flaccid paralysis without sensory loss.

WHO recommends lab diagnosis of polio must be done by isolation and identification of polio virus in the stool ,with specific identification of wild –type and vaccine strains.

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In suspected of poliomyelitis two stool sample collected 24-48 hrs apart

80-90% isolation of virus in acute phase.

< 20% isolation b/w 3-4 weeks

Ideally 8-10gm stool sample

Proper cold chain

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Differential diagnosis

All causes of acute flaccid paralysis

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AFP

Paralysis of acute onset

i.e

less than 4weeks and affected limbs are floppy or flaccid or limp.

Tone diminished, DTR diminished.

Sensation not affected

Case definition

: any child aged less than 15yrs who has acute onset flaccid paralysis for which no obvious cause(severe trauma, electrolyte imbalance) is found or paralytic illness in a person of any age in which polio is suspected

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AFP

causes

Disorder of muscle: e.g.

polymyositis

, viral

myositis

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Treatment only supportive

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PreventionWHO recommends 4 strategy for global eradication of polio-1-routine vaccination2-NIDs

3-AFP surveillance

3- Mop-up immunization