TAG: GS 3: ECOLOGY AND ENVIRONMENT
THE CONTEXT: Wastewater surveillance has emerged as a valuable tool for monitoring the presence of pathogens in communities before they are detectable via conventional laboratory methods.
- This approach has been effectively employed for decades in tracking water-borne diseases such as polio, utilizing sewage samples to detect viruses.
- The method’s cost-effectiveness and ability to pre-emptively identify pathogen presence make it a promising avenue for disease surveillance.
Successes in Pandemic Monitoring and Global Context
- During the COVID-19 pandemic, wastewater surveillance played a pivotal role in identifying the emergence and spread of variants like the XBB.1.16 Omicron variant in Bengaluru, as conducted by the Tata Institute for Genetics and Society (TIGS).
- This approach also aids in assessing the extent of virus spread and monitoring viral load, providing valuable insights for public health responses.
- Researchers in developed nations have advocated expanding wastewater surveillance beyond COVID-19 to track diseases like dengue, malaria, Zika, and typhoid.
- However, the application of this surveillance approach requires considerations beyond mere feasibility, taking into account geographical context, pathogen biology, and the local sewage infrastructure.
Challenges in Implementing Wastewater Surveillance for Vector-Borne Diseases in India
- In India, diseases like malaria and dengue are endemic, persisting throughout the year, unlike in developed countries where these infections are sporadic and seasonal.
- Additionally, a complex aspect in the Indian context is the presence of multiple reservoir hosts, including non-human primates, for these vector-borne diseases.
- Detection of malaria and dengue pathogens through wastewater surveillance faces substantial challenges.
- The low viral shedding in the case of dengue makes it challenging to detect viral RNA in wastewater at levels comparable to SARS-CoV-2 RNA.
- Moreover, the presence of diverse animal hosts for these diseases in tropical countries like India complicates the exclusive identification of human-originated pathogens in wastewater samples.
The Need for Complementary Approaches
- While wastewater surveillance offers insights, it cannot independently provide a comprehensive understanding of vector-borne diseases due to the involvement of multiple reservoir hosts.
- The study suggests the integration of mosquito surveillance alongside wastewater analysis for a more holistic approach to combating vector-borne illnesses.
Selection of Priority Pathogens for Surveillance
- When considering pathogens for wastewater surveillance, stability in wastewater and consistent shedding in faecal material or urine are essential criteria.
- However, in the case of diseases like malaria and dengue, exclusivity in human origin poses a significant challenge.
Insights from Bangladesh’s Wastewater Surveillance Program
- Bangladesh initiated a proof-of-concept wastewater surveillance program targeting vaccine-preventable pathogens like Salmonella typhi, Vibrio cholerae, and rotavirus alongside SARS-CoV-2.
- It emphasized the importance of considering sanitation systems and host-parasite geography when selecting priority pathogens for surveillance.
Conclusion: Challenges and Considerations
- Wastewater surveillance presents an opportunity for disease tracking, yet its application for endemic vector-borne diseases in India demands a cautious approach.
- The complexities arising from multiple hosts and continuous transmission throughout the year necessitate a comprehensive understanding of the limitations and challenges in effectively utilizing this surveillance method for diseases like malaria and dengue.
- Integrating multiple surveillance approaches and accounting for geographical and biological nuances remain crucial in leveraging the potential of wastewater surveillance for disease monitoring in India.