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Global Polio Resurgence: Key Points and Analysis

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Global Polio Resurgence: Key Points and Analysis

Why in News

  • Polio cases and environmental samples globally have shown both wild poliovirus (WPV) and vaccine-derived poliovirus (cVDPV), raising concerns about a resurgence.
  • WHO surveillance highlights the detection of poliovirus in wastewater across several countries.

Current Global Scenario

  • Countries Reporting Poliovirus:
    • Wild Poliovirus (WPV1): Pakistan (4 cases), environmental samples in other countries.
    • Circulating Vaccine-Derived Poliovirus (cVDPV2): Cameroon, Cote D’Ivoire, Chad, Nigeria.
    • Wastewater Detection: Finland, Germany, Poland, Spain, UK, and Gaza.
  • Vaccination and Surveillance:
    • Routine immunization coverage in affected countries: 85-95% (3 doses of IPV).
    • Subnational immunity gaps remain, necessitating continued vaccination and surveillance.

Vaccine Controversy and Transmission Routes

  • Vaccines in Use:

    • Oral Polio Vaccine (OPV): Effective but can cause vaccine-derived poliovirus (cVDPV).
    • Inactivated Polio Vaccine (IPV): Safer and non-transmissible but logistically challenging to implement universally.

  • Transmission Debate:

    • Historically accepted faecal-oral route questioned by recent studies.
    • Evidence supports respiratory transmission as critical:
      • Virus shedding in the throat enables airborne spread.
      • Faecal-oral transmission unlikely to cause outbreaks without concurrent enteric diseases.

Policy Recommendations

  • Shift from OPV to IPV for better global eradication prospects:

    • IPV prevents both WPV and cVDPV without risk of transmission.
    • Gradual OPV-to-IPV transition needed, country by country.

  • Enhanced surveillance and closing immunity gaps are crucial for global eradication.

Mains Examination Question

Discuss the resurgence of polio worldwide and analyze the need for a shift in vaccination strategy to achieve global polio eradication. (250 words)

Prelims Question Example

Consider the following statements regarding polio transmission and vaccines:

  1. Oral Polio Vaccine (OPV) can lead to vaccine-derived poliovirus.
  2. Inactivated Polio Vaccine (IPV) is a transmissible form of vaccine.
  3. Recent studies suggest respiratory transmission as a primary route for poliovirus spread.

Which of the above statements is/are correct?

  • (a) 1 only
  • (b) 1 and 3 only
  • (c) 2 and 3 only
  • (d) 1, 2, and 3

Correct Answer: (b) 1 and 3 only.
Explanation: Statement 1 is correct; OPV can cause cVDPV. Statement 2 is incorrect as IPV is non-transmissible. Statement 3 is correct based on recent findings on respiratory transmission.

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Polio Virus: Overview and Key Facts

What is Polio Virus?

  • Polio virus, a member of the Picornaviridae family, is a highly infectious virus that primarily affects the nervous system, causing paralysis or even death in severe cases.
  • It is transmitted through the faecal-oral route or, as recent studies suggest, respiratory droplets.

Types of Polioviruses

  1. Wild Poliovirus (WPV):
    • Naturally occurring strain.
    • Types: WPV1, WPV2 (eradicated in 2015), and WPV3 (eradicated in 2019).
  2. Vaccine-Derived Poliovirus (VDPV):
    • Mutated strain of the weakened virus from the oral polio vaccine.
    • Types: cVDPV1, cVDPV2, cVDPV3.

Symptoms

  • Asymptomatic Cases: Majority (~90%) show no symptoms.
  • Minor Illness: Fever, sore throat, nausea.
  • Severe Cases:
    • Paralytic Poliomyelitis: Affects spinal cord or brainstem.
    • Post-Polio Syndrome: Long-term muscle weakness decades after infection.

Vaccines

  1. Oral Polio Vaccine (OPV):
    • Live-attenuated vaccine.
    • Advantages: Easy to administer, induces gut immunity.
    • Drawback: Can lead to vaccine-derived poliovirus (VDPV).
  2. Inactivated Polio Vaccine (IPV):
    • Killed virus vaccine, administered via injection.
    • Advantages: Safer, prevents paralysis and transmission.
    • Limitation: Does not induce gut immunity effectively.

Global Polio Eradication Efforts

  • Global Polio Eradication Initiative (GPEI):
    • Launched in 1988 by WHO, UNICEF, and Rotary International.
    • Major Successes:
      • WPV2 and WPV3 eradicated.
      • Over 99% reduction in global polio cases.
    • Challenges:
      • Persistence of WPV1 in Pakistan and Afghanistan.
      • Emergence of cVDPVs.

Current Status (2024)

  • Regions Reporting Polio:
    • WPV1: Pakistan and Afghanistan.
    • cVDPV: Detected in Africa, Europe, and the Middle East.
  • Vaccination Coverage:
    • High in many countries (85-95%) but subnational gaps exist.

Transmission

  • Routes:
    • Faecal-Oral Route: Contaminated water or food.
    • Respiratory Droplets: Evidence points to airborne spread.

Preventive Measures

  1. Universal vaccination coverage using IPV or OPV.
  2. Robust disease surveillance for early detection.
  3. Community hygiene and sanitation improvements.
  4. Timely immunization campaigns in outbreak areas.

Prelims MCQ

Which of the following statements regarding the polio virus is/are correct?

  1. Wild poliovirus type 3 has been eradicated globally.
  2. Inactivated polio vaccine (IPV) induces better gut immunity than oral polio vaccine (OPV).
  3. Polio can spread through respiratory droplets as well as the faecal-oral route.

Options:
(a) 1 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2, and 3

Correct Answer: (b) 1 and 3 only.
Explanation: WPV3 is eradicated (Statement 1). IPV does not induce better gut immunity than OPV (Statement 2 is incorrect). Polio can spread through respiratory droplets and faecal-oral routes (Statement 3).

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WHO Efforts in Polio Eradication

The World Health Organization (WHO) has been at the forefront of global polio eradication efforts through coordinated campaigns, partnerships, and innovations. These efforts are part of the Global Polio Eradication Initiative (GPEI) launched in 1988.

Key Efforts by WHO

1. Global Polio Eradication Initiative (GPEI)

  • Launched: 1988.
  • Partners: WHO, UNICEF, Rotary International, CDC (Centers for Disease Control and Prevention), and Gavi.
  • Objective: Eradicate polio through vaccination, surveillance, and public health interventions.

2. Mass Vaccination Campaigns

  • Pulse Polio Immunization Program: Conducted in collaboration with governments to provide polio drops to children under 5 years of age.
  • Switch from OPV to IPV:
    • Phased introduction of Inactivated Polio Vaccine (IPV) in routine immunization.
    • Gradual withdrawal of Oral Polio Vaccine (OPV) to reduce vaccine-derived poliovirus (VDPV).

3. Surveillance Systems

  • Environmental Surveillance:
    • Monitoring sewage and wastewater for poliovirus.
    • Detection in regions like Europe, Africa, and the Middle East.
  • Acute Flaccid Paralysis (AFP) Surveillance:
    • Tracking cases of paralysis in children for early detection of polio outbreaks.

4. Focus on High-Risk Areas

  • Addressing persistent polio in Pakistan and Afghanistan where wild poliovirus (WPV1) remains endemic.
  • Targeting countries with vaccine-derived poliovirus (VDPV) outbreaks.

5. Community Engagement and Awareness

  • Partnerships with local governments and NGOs for community mobilization.
  • Education campaigns to dispel vaccine myths and increase immunization coverage.

6. Technical and Financial Support

  • WHO provides technical expertise to strengthen health systems in endemic and outbreak-prone countries.
  • Financial aid for vaccination drives, training programs, and surveillance systems.

7. Innovations in Vaccine Delivery

  • Development of bivalent oral polio vaccine (bOPV) for WPV1 and WPV3.
  • Deployment of novel oral polio vaccine (nOPV) to combat vaccine-derived strains.

8. Emergency Response

  • WHO’s Rapid Response Teams address polio outbreaks promptly.
  • Deployment of vaccines and resources to affected areas within days.

Achievements

  1. Global Progress:
    • Reduction of polio cases by over 99% since 1988.
    • Eradication of WPV2 (2015) and WPV3 (2019).
  2. High Routine Immunization: Achieved 85-95% coverage in many countries.

Challenges

  1. Persistent Polio in Endemic Areas:
    • Pakistan and Afghanistan remain polio-endemic due to insecurity and misinformation.
  2. Vaccine-Derived Poliovirus (VDPV):
    • Outbreaks in under-vaccinated regions.
  3. Subnational Immunity Gaps:
    • Low coverage in marginalized or conflict-affected areas.

Prelims Question Example

Which of the following is not a partner in the Global Polio Eradication Initiative (GPEI)?

(a) WHO
(b) UNICEF
(c) Rotary International
(d) World Bank

Answer: (d) World Bank

Explanation: The World Bank is not a direct partner in the GPEI. Key partners include WHO, UNICEF, Rotary International, CDC, and Gavi.

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History of Polio Virus

Early Observations

  • Prehistoric Evidence:

    • Polio-like symptoms observed in ancient artwork and skeletons.
    • Egyptian stele (~1400 BCE): Depiction of a priest with a withered leg, likely from polio.

  • First Documented Cases:

    • Descriptions of polio outbreaks appeared as early as the 18th century in Europe.
    • Recognized as a distinct clinical entity by Jakob Heine in 1840.

19th and Early 20th Century

  • Epidemics:

    • 19th-century outbreaks were recorded in Europe and the United States.
    • Major outbreaks began in the 1900s, leading to widespread paralysis and death.

  • Transmission and Causes:

    • Polio transmission was first thought to be respiratory.
    • Later identified as spreading primarily via the faecal-oral route in areas with poor sanitation.

  • Discovery of Poliovirus:

    • In 1908, Karl Landsteiner and Erwin Popper identified the virus responsible for polio.

Development of Vaccines

  1. Salk Vaccine (Inactivated Polio Vaccine - IPV):

    • Developed by Jonas Salk in 1955.
    • Used an inactivated (killed) form of the virus.
    • Successfully reduced polio cases in vaccinated populations.

  2. Sabin Vaccine (Oral Polio Vaccine - OPV):

    • Developed by Albert Sabin in 1961.
    • Live-attenuated vaccine administered orally.
    • Easier to distribute and provided broader immunity through gut replication.

Global Polio Eradication Efforts

  • 1950s–1970s:

    • Routine immunization programs initiated in developed countries.
    • Polio eradicated in the U.S. and much of Europe by the 1970s.

  • 1988: Global Polio Eradication Initiative (GPEI):

    • Launched by WHO, Rotary International, UNICEF, and CDC.
    • Target: Eradication of polio worldwide through vaccination and surveillance.

Recent Developments

  • 2000s:

    • Wild poliovirus (WPV) eradicated in most regions except Pakistan and Afghanistan.
    • Challenges with vaccine-derived poliovirus (VDPV) emerged, linked to OPV usage.

  • 2020s:

    • Focus shifted to using Inactivated Polio Vaccine (IPV).
    • Wild poliovirus type 2 (WPV2) declared eradicated in 2015, followed by type 3 (WPV3) in 2019.
    • Efforts intensified to address vaccine resistance and under-vaccination.

Key Milestones

  1. 1908: Discovery of the poliovirus.
  2. 1955: Launch of the Salk vaccine (IPV).
  3. 1961: Introduction of the Sabin vaccine (OPV).
  4. 1988: Launch of the Global Polio Eradication Initiative.
  5. 2015: Eradication of WPV2.
  6. 2019: Eradication of WPV3.

Prelims Question Example

Consider the following statements regarding the history of polio:

  1. Polio was first identified as a distinct disease by Karl Landsteiner.
  2. The Salk vaccine is an oral polio vaccine (OPV).
  3. The Global Polio Eradication Initiative was launched in 1988.

Which of the above statements is/are correct?

  • (a) 1 only
  • (b) 3 only
  • (c) 1 and 3 only
  • (d) 1, 2, and 3

Answer: (b) 3 only.
Explanation:

  • Statement 1 is incorrect; Jakob Heine identified polio as a distinct disease.
  • Statement 2 is incorrect; the Salk vaccine is an inactivated polio vaccine (IPV).
  • Statement 3 is correct; the GPEI was launched in 1988.
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Polio Virus in India: Key Highlights

Introduction

  • Polio, a highly infectious disease caused by the poliovirus, posed a significant public health challenge in India during the 20th century.
  • The disease primarily affected children under 5, causing paralysis and sometimes death.

History of Polio in India

  1. Pre-1980s:

    • India experienced widespread polio outbreaks, with thousands of children paralyzed annually.
    • Poor sanitation and limited access to vaccines contributed to its prevalence.

  2. 1980s–1990s:

    • In 1988, the Global Polio Eradication Initiative (GPEI) was launched.
    • India became a priority country due to its high number of cases.
    • Introduction of the Pulse Polio Immunization Program in 1995 marked a significant step.

  3. 2000s:

    • Massive vaccination campaigns were conducted, targeting every child under 5 years.
    • Surveillance systems were established to detect and respond to polio cases.

  4. 2011:

    • The last case of wild poliovirus (WPV) was reported in India in Howrah, West Bengal, on January 13, 2011.
    • India was removed from the list of polio-endemic countries in 2012.

  5. 2014:

    • India was declared polio-free by the World Health Organization (WHO) on March 27, 2014.

Key Initiatives and Programs

  1. Pulse Polio Immunization Program (1995):

    • Nationwide program to provide Oral Polio Vaccine (OPV) to children under 5.
    • Conducted National Immunization Days (NIDs) twice a year.

  2. Intensive Vaccination Drives:

    • Large-scale campaigns involved government, NGOs, and community participation.
    • Targeted high-risk areas, such as slums and remote villages.

  3. Surveillance and Monitoring:

    • Acute Flaccid Paralysis (AFP) Surveillance: Monitored cases of sudden paralysis.
    • Environmental Surveillance: Regular testing of sewage samples for poliovirus.

  4. Transition to Inactivated Polio Vaccine (IPV):

    • Introduced in 2016 to reduce the risk of vaccine-derived poliovirus (VDPV).

Challenges Overcome

  1. High Population and Birth Rate:
    • Ensuring every child received vaccination was a monumental task.
  2. Geographic Barriers:
    • Difficult terrain and remote locations hindered access to immunization.
  3. Vaccine Hesitancy:
    • Misinformation and cultural resistance required extensive awareness campaigns.
  4. Cross-Border Transmission:
    • Coordination with neighboring countries like Pakistan and Bangladesh was critical.

Current Status

  1. Polio-Free Certification:

    • India remains polio-free since 2014.
    • No wild poliovirus cases have been reported since 2011.

  2. Vaccine-Derived Poliovirus (VDPV):

    • Surveillance continues to detect and manage sporadic cases of VDPV.

  3. Routine Immunization:

    • Vaccination coverage is maintained through the Universal Immunization Program (UIP).

Impact of Polio Eradication

  1. Public Health Success:
    • Eradication of polio has saved millions of children from paralysis and death.
  2. Strengthened Health Infrastructure:
    • The campaign improved surveillance, immunization delivery, and healthcare systems.
  3. Global Recognition:
    • India’s success became a model for other developing countries.

Prelims MCQ Example

Which of the following statements about polio in India is correct?

  1. The last wild poliovirus case in India was reported in 2014.
  2. India was declared polio-free by WHO in 2014.
  3. Pulse Polio Immunization Program in India was launched in 1988.

Options:

  • (a) 1 only
  • (b) 2 only
  • (c) 2 and 3 only
  • (d) 1, 2, and 3

Answer: (b) 2 only.
Explanation:

  • Statement 1 is incorrect; the last case was in 2011.
  • Statement 2 is correct; India was declared polio-free in 2014.
  • Statement 3 is incorrect; Pulse Polio Immunization Program started in 1995.
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