Rapid urbanisation in India has created both the infrastructure density necessary for modern public health surveillance and the vulnerabilities that make such surveillance urgent.

GS1 Urbanisation
Rapid urbanisation in India has created both the infrastructure density necessary for modern public health surveillance and the vulnerabilities that make such surveillance urgent. In this context, examine the role of wastewater-based epidemiology as a complementary tool in urban disease monitoring.

Examine

  • 15 marks
  • 8 min
  • 250 words
  • Medium

The Hindu

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Introduction

Rapid urbanisation in India has increased both the feasibility and necessity of advanced disease surveillance. Dense sewage networks, expanding municipal systems and high population concentration have made wastewater-based epidemiology (WBE) an important complementary tool for monitoring infectious diseases in cities.

How Urbanisation Enables WBE

  • Urban centres possess concentrated sewage infrastructure and ward-based governance systems suitable for large-scale sampling.

    • For example, Bengaluru’s 198 BBMP wards and network of 26 sewage treatment plants (STPs) provide viable surveillance points.

  • The same urban density that enables WBE also accelerates disease transmission through overcrowding, mobility and sanitation stress, making continuous monitoring urgent.

Role of WBE in Disease Monitoring

  • WBE analyses sewage samples for viral fragments, enabling estimation of community-level infection trends independent of individual testing behaviour.
  • Studies have shown strong reliability, including Pearson correlation coefficients above 0.8 between wastewater viral loads and reported COVID-19 cases.
  • Global experiences from the Netherlands and the United States demonstrated that wastewater signals often identified COVID-19 surges before widespread clinical confirmation.
  • In India, variants such as XBB (April 2023) and JN.1 (December 2023) were detected in sewage even when clinical case counts remained low.
  • Similar findings emerged from pilot studies in Chennai and Hyderabad, particularly when public testing declined.

Limitations of WBE

  • WBE is not always an effective early-warning system.

    • During the Omicron wave in Bengaluru, wastewater viral rise occurred almost simultaneously with clinical infections.

  • Signals generally emerge only after substantial community transmission has already occurred.

  • It cannot identify infected individuals, requiring parallel sentinel clinical surveillance.

Way Forward

  • Integrate WBE into the National Disease Surveillance Programme and the One Health framework.
  • Standardise sampling protocols, data sharing and municipal laboratory capacity.

Conclusion

Thus, WBE should be viewed as a complementary rather than replacement mechanism, strengthening parallel surveillance architecture and improving urban pandemic preparedness in India.