The global battle against polio has seen progress since the World Health Organisation’s call for eradication in 1988. As of 2024, polio remains endemic in only two countries – Pakistan and Afghanistan. Despite this progress, recent detections of poliovirus in wastewater across Europe signal potential risks, underscoring the need for vigilance in vaccination efforts.
About Polio and Its Transmission
Polio, or poliomyelitis, is a highly contagious viral disease. The poliovirus primarily spreads via the faecal-oral route. It can lead to paralysis within hours of infection. Approximately one in 200 infections results in irreversible paralysis. Among those paralysed, 5–10% may die due to respiratory failure.
Global Progress in Eradication
Since 1988, the number of polio cases has decreased by over 99%. The world has witnessed the near eradication of one poliovirus strain. However, Pakistan and Afghanistan continue to report regular transmissions. The global health community has made tremendous strides, yet challenges remain.
Recent Wastewater Surveillance Findings
Recently, poliovirus was detected in wastewater samples from Germany, Spain, and Poland. Although no cases of paralytic disease were reported, these findings serve as a warning. They highlight the importance of maintaining high vaccination coverage to prevent outbreaks.
Vaccine-Derived Poliovirus Strains
Vaccine-derived poliovirus strains can emerge from the weakened virus in oral polio vaccines. If these strains circulate among under-immunised populations, they may revert to a virulent form. This has raised concerns as some countries report detections without corresponding paralytic cases.
Vaccination Coverage and Its Importance
In 2023, vaccination coverage among one-year-olds in Europe reached around 95%. This exceeds the 80% herd immunity threshold. However, in countries like Spain, Germany, and Poland, coverage with three doses ranged from 85% to 93%. Under-immunised groups remain vulnerable, necessitating ongoing vaccination efforts.
The Impact of Humanitarian Crises
Humanitarian crises, including conflicts and climate change, disrupt vaccination programmes. As of 2024, 30% of countries have vaccine coverage below 80%. In some areas, coverage plummets to as low as 36%. These challenges threaten to reverse decades of progress in polio eradication.
The Role of Wastewater Surveillance
Wastewater surveillance has gained prominence as a tool for early disease detection. It provides valuable vital information about community health. By analysing wastewater, health officials can identify potential outbreaks and take preventive measures. This approach has become increasingly vital in the context of global health.
Future Directions for Polio Eradication
Continued efforts are essential to safeguard immunisation programmes. The COVID-19 pandemic has brought into light that viruses do not respect borders. A sustained commitment to vaccination is crucial to prevent polio’s resurgence. The ongoing vigilance and adaptation of strategies are necessary to maintain public health.
Questions for UPSC:
- Examine the role of vaccination in controlling infectious diseases, using polio as a case study.
- Discuss the implications of wastewater surveillance on public health policies in the context of emerging diseases.
- Critically discuss the challenges faced in global vaccination efforts against polio and their impact on public health.
- With suitable examples, discuss the effects of humanitarian crises on vaccination coverage and disease resurgence.
Answer Hints:
1. Examine the role of vaccination in controlling infectious diseases, using polio as a case study.
- Vaccination has led to a 99% decrease in polio cases globally since 1988.
- Oral polio vaccines have been crucial in eradicating specific poliovirus strains.
- Immunization creates herd immunity, protecting vulnerable populations from outbreaks.
- High vaccination coverage prevents the emergence of vaccine-derived poliovirus strains.
- Continued vaccination efforts are essential to maintain progress and prevent resurgence.
2. Discuss the implications of wastewater surveillance on public health policies in the context of emerging diseases.
- Wastewater surveillance detects viral presence before clinical cases emerge, enabling early intervention.
- It marks gaps in vaccination coverage, prompting public health responses to boost immunization.
- Routine testing can identify new strains of viruses, informing vaccine development and policy.
- Data from wastewater can guide resource allocation and healthcare access improvements.
- This method enhances overall disease surveillance and preparedness against future outbreaks.
3. Critically discuss the challenges faced in global vaccination efforts against polio and their impact on public health.
- Humanitarian crises disrupt vaccination campaigns, leading to decreased coverage in affected regions.
- Vaccine hesitancy and misinformation can hinder public willingness to participate in immunization programs.
- Logistical challenges in delivering vaccines, especially in remote or conflict-affected areas, persist.
- Under-immunized populations remain at risk, allowing for the potential resurgence of polio.
- Global disparities in healthcare access complicate uniform vaccination efforts across regions.
4. With suitable examples, discuss the effects of humanitarian crises on vaccination coverage and disease resurgence.
- In conflict zones, such as Syria, vaccination campaigns are severely disrupted, leading to outbreaks.
- Natural disasters can displace populations, making immunization efforts difficult to implement.
- Countries with low vaccination coverage, like those affected by climate change, see increased disease incidence.
- For instance, polio cases rose in Afghanistan due to ongoing conflict and healthcare access issues.
- Humanitarian crises can exacerbate existing health disparities, resulting in higher susceptibility to diseases.
