Global Polio Resurgence and Reevaluating Basics
- December 27, 2024
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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Global Polio Resurgence and Reevaluating Basics
Sub: Sci
Sec: Health
Why in News
- The resurgence of polio globally, with environmental samples and human cases detecting both wild poliovirus (WPV) and vaccine-derived poliovirus (cVDPV), highlights the fragility of global health achievements.
Current Situation:
- WHO reported poliovirus detection in wastewater in Finland, Germany, Poland, Spain, and the UK (2024). No confirmed cases yet, but the findings emphasize vaccination and surveillance.
- Pakistan: 4 WPV1 cases, 8 positive samples.
- Africa: Cases detected in Cameroon, Côte d’Ivoire, Chad, and Nigeria.
About Polio (Poliomyelitis):
- Polio is a highly infectious viral disease caused by the poliovirus, primarily affecting children under the age of 5.
- The virus spreads predominantly through the faecal-oral route, often via contaminated water or food, and can also transmit through oral-oral contact.
- Symptoms:
- Approximately 70% of infections are asymptomatic.
- Around 25% present mild symptoms such as fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the limbs.
- A small proportion of cases lead to irreversible paralysis, typically in the legs. Among those paralyzed, 5–10% may die due to immobilization of breathing muscles.
- Prevention: Polio is preventable through vaccination. The two primary vaccines are:
- Inactivated Poliovirus Vaccine (IPV): Administered via injection; contains inactivated virus.
- Oral Poliovirus Vaccine (OPV): Administered orally; contains a live, attenuated (weakened) virus.
About Wild Poliovirus (WPV):
- Wild polioviruses are naturally occurring strains of poliovirus circulating in the environment.
- Serotypes:
- Type 1: The only wild poliovirus strain still in circulation as of 2024.
- Type 2: Declared eradicated in September 2015; last detected in India in 1999.
- Type 3: Declared eradicated in October 2019; last detected in November 2012.
- As of 2024, wild poliovirus type 1 remains endemic in two countries: Pakistan and Afghanistan.
About vaccine-derived poliovirus (VDPV):
- Vaccine-Derived Poliovirus (VDPV) refers to strains of poliovirus that originate from the oral polio vaccine (OPV).
- While OPV effectively protects against poliovirus, it contains live, attenuated (weakened) virus strains that can occasionally revert to a virulent form, leading to cases of paralysis.
Classification of VDPV:
WHO classifies VDPV cases into three categories:
- Circulating Vaccine-Derived Polioviruses (cVDPVs): Emerges in populations with low vaccination coverage, where the vaccine virus can spread among unvaccinated individuals.
- Immune-Deficiency Associated VDPV (iVDPV): Occurs in individuals with primary immunodeficiencies who may excrete the vaccine-derived virus for an extended period, sometimes years.
- Ambiguous Vaccine-Derived Polioviruses (aVDPVs): Cases where it is unclear if the virus is derived from vaccine strains or has characteristics of both wild and vaccine strains.
Polio in India:
- India was declared polio-free in 2014, marking a significant public health achievement.
- Prior to eradication, India conducted extensive vaccination campaigns, delivering around 1 billion doses of polio vaccine to 172 million children each year over four years leading up to the last reported case.
- Post-eradication, India continues to maintain high immunization coverage to prevent reintroduction of the virus.