POLIOMYELITIS

Andrea R Salins

Poliomyelitis is an acute viral infection caused by a RNA virus

Pre vaccination era-polio was worldwide1988-WHO resolved to eradicate polio 1988-125 endemic countries2008-4 endemic countries(PAIN)Last reported case in India was in 2011At present its endemic in PAN countries

EPIDEMIOLOGYAGENTCausative agent-Enterovirus belonging to Picornaviridae

Serotype-1,2,3(most outbreaks due to type 1)Reservoir-only manInfectious material-faeces and oropharyngeal secretion of infected person

Period of communicability-7-10 days before and after onset of symptoms.

HOSTAge-children(6 mnth-3 yr more vulnerable)Sex-MALE:FEMALE::3:1Risk factors-Fatigue, trauma, IM injection, tonsillectomy done during epidemics

Immunity

ENVIRONMENTAL FACTORSRainy seasonPoliovirus survives longer in cold environment

MODE OF TRANSMISSIONFaeco-oral-developing countriesDroplet-acute phase of infection

CLINICAL SPECTRUMInapparent (subclinical) infection91-96%No presenting symptomsRecognition by virus isolation or rising antibody titre

Abortive polio(minor illness)4-8%Mild self limiting Quick recoveryRecognition by virus isolation or rising antibody titre

Non paralytic polio1%Stiffness and pain in neck and back Lasts for 2-10 daysRapid recoveryDisease mimics aseptic meningitis

Paralytic polio<1%Virus invades CNS causing various degrees of paralysis

Predominant sign-Asymmetrical flaccid paralysis

h/o fever at the time of onset of paralysis indicative of polio

Associated symptoms

Signs of meningeal irritationTripod sign

Descending paralysisNo sensory lossRespiratory insufficiency can lead to death

PREVENTIONIMMUNIZATION2 TYPESInactivated(Salk)polio vaccineOral(Sabin)polio vaccine

Inactivated Made from selected WPV strainsHarvested viral components are inactivated with formaldehyde

Dose-Primary course:4 inoculation 1st three doses at interval of 1-2 month 4th dose 6-12 month after third dose Additional dose-prior to school entry and then every five year up to 8yrs of age

Drawbacks-no benefit to the community immunity not rapid shoudn’t be administered during epidemicAdvantage-safe

ORALLive attenuated vaccine , trivalent vaccineDose-2 drops

EPIDEMIOLOGICAL INVESTIGATION

Faeces sample forwarded to labWHO should be notifiedWithin epidemic area OPV should be provided to all above 6wks of age who have not been previously immunized or immune status is unknown

STRATEGIES FOR ERADICATION IN INDIAPulse polio immunization daysHigh level of immunization coverageMonitor OPV coverage at district level and below

Improved surveillance capable of detecting all cases of AFP

Rapid case investigationArrange follow up at 60 daysConduct outbreak control for confirmed or suspected cases

Sustain and maintain high level of routine immunization coverage of infantsStrategyRoutine immunization of every child aged<1 yr with at least 3 doses of OPV at age of 6,10,14 weeks

Conduct pulse polio immunization days every year until polio is completely eradicated

Monitor OPV coverage in all districts at district level and below

PULSE POLIO IMMUNIZATIONRefers to sudden, simultaneous, mass administration of OPV on a single day to all children 0-5 years of age regardless of prior immunization status

It occurs in 2 rounds about 4-6 wks apart during low transmission season of polio(between November-February)

Doses of OPV are extra dosesChildren should receive scheduled doses as well as PPI’s

Vaccines use vial monitors

Acute flaccid paralysis surveillance Introduced in 1997Acute flaccid paralysis is sudden onset of flaccid

paralysis(LMN type)of limb of less than 4 weeks duration in child below 15 years with decreased or loss of tone and deep tendon reflex and the limb is floppy or flaccid without sensory loss

Objectives -to identify high risk areas -to monitor progress -to certify a country polio freeTypes –routine surveillance - active surveillance

LINE LISTINGStarted in 1989 to check for duplication, year of

onset of illness, identification of high risk pocket groups and documentation of high risk age groups

All cases of AFP should be reported to chief medical officer/district immunization officer with following details

Name ,age, and sex of patients Fathers name and complete address Vaccination status Date of onset of paralysis and date of reporting Clinical diagnosis Doctors name, address and phone number

MOPPING UPAFP surveillance data are used to identify the final chains of wild poliovirus transmission in each geographical area

In these area,2 doses of OPV are administered to all children<5yrs,regardless of their prior immunization status by immunization teams that go house to house

Last stage in polio eradication

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