Poliomyelitis (Polio) is a viral infectious disease that can cause flaccid
paralysis by affecting the central nervous system in about 0.5% of cases.
Etiopathogenesis of Poliovirus
1. Causative Agent:
- Poliovirus is an enterovirus belonging
to the Picornaviridae family.
- There are three serotypes: PV1, PV2,
and PV3 (PV1 is most commonly associated with paralysis).
2. Mode of Transmission:
- Fecal-oral route (primary)
- Oral-oral route (less common)
3. Pathogenesis:
- Entry: Virus enters through the mouth and multiplies in the
oropharynx and gastrointestinal tract (lymphoid tissue like tonsils and
Peyer's patches).
- Viremia: Virus enters the bloodstream and may spread to other
sites.
- CNS
Invasion: In <1% of cases, the virus
crosses the blood-brain barrier or is transported via peripheral nerves to
the central nervous system (CNS).
- Neuronal
Damage: The virus targets anterior
horn cells of the spinal cord, causing motor neuron
destruction, leading to flaccid paralysis.
- Outcomes:
- Asymptomatic
(90–95%)
- Minor
illness (4–8%) –
fever, sore throat
- Non-paralytic
poliomyelitis (<1%)
– aseptic meningitis
- Paralytic
poliomyelitis (<0.5%)
Pharmacotherapy of Poliovirus
There is no specific antiviral
treatment for poliovirus. Management is primarily supportive
and preventive:
1. Supportive Treatment:
- Bed
rest, analgesics
for pain
- Physical
therapy to prevent deformities and
improve mobility
- Ventilatory
support (iron lung or modern
ventilators) in case of respiratory muscle paralysis
2. Preventive Pharmacotherapy
(Vaccination):
- OPV may rarely cause vaccine-associated paralytic
polio (VAPP) or circulating vaccine-derived poliovirus
(cVDPV).
- IPV is introduced to mitigate VAPP and cVDPV risks.
Pulse Polio Immunization in India
- Launched in 1995 as part of the global
polio eradication initiative following the 1988 World Health
Assembly resolution.
- Targets children aged 0–5 years with
polio drops during national and sub-national rounds.
Key Milestones
- 1995: Pulse Polio Programme launched
- 2009: India reported half of the global polio cases
- 2011: Last polio case in India
- 2012: WHO removed India from the list of endemic countries
- 2014: India declared polio-free
Aims and Objectives
- Immunize every child, especially in remote areas
- Ensure no child is missed during
immunization
- Timely reporting of acute flaccid paralysis
(AFP) cases and stool sample collection
- Rapid outbreak response immunization (ORI)
- Maintain strong surveillance systems
Steps to Maintain Polio-Free Status
- Annual high-quality immunization rounds
- Surveillance for any virus importation or circulation
- Environmental
surveillance
through sewage sampling
Polio Eradication and Preparedness Efforts in India
Rapid Response and Emergency Plans
- All States/UTs have Rapid Response Teams (RRTs)
and Emergency Preparedness and Response Plans (EPRPs) to
handle any polio outbreaks.
Preventing Importation
- Continuous
Vaccination Teams (CVTs)
deployed at international borders to vaccinate eligible children around
the clock.
- As of August 31, 2015, approximately 7.8
million children vaccinated with OPV.
- Since March 2014, mandatory
polio vaccination for international travelers to and from India
and affected countries like Afghanistan, Nigeria, Pakistan, etc.
- A rolling stock of OPV is maintained
for emergency response.
Introduction of IPV in Routine Immunization
- In line with the Polio Eradication &
Endgame Strategic Plan 2013–2018, India introduced the Inactivated
Poliovirus Vaccine (IPV) in 2015.
- IPV is given with the third dose of OPV
at 14 weeks of age for infants.
Programme Outcomes
- Over 17.4 crore children under 5 years
receive polio drops annually.
- Last
polio case reported on 13 January
2011 in Howrah, West Bengal.
- WHO
removed India from
the list of polio-endemic countries on 24 February 2012.
