Soil-based environmental DNA enables detection of Oncomelania hupensis quadrasi and Schistosoma japonicum microhabitats for schistosomiasis japonica surveillance and control in the Philippines – Infectious Diseases of Poverty

Advancing Sustainable Development Goals through Innovative Schistosomiasis Surveillance

Introduction: Aligning Disease Control with Global Sustainability Targets

• This report details a study on a soil-based environmental DNA (eDNA) detection system for Oncomelania hupensis quadrasi (snail host) and Schistosoma japonicum (parasite).
• The methodology directly supports several Sustainable Development Goals (SDGs), primarily SDG 3 (Good Health and Well-being), by providing an advanced tool to combat neglected tropical diseases like schistosomiasis.
• The research also contributes to SDG 6 (Clean Water and Sanitation) and SDG 15 (Life on Land) by enabling precise monitoring of disease vectors and parasites in terrestrial and aquatic ecosystems, thereby helping to protect community health and biodiversity.

Methodology and Key Findings: A Technological Leap for Public Health and Environmental Monitoring

Application and Efficacy of Soil-Based eDNA Detection

1. The study successfully demonstrated the application of soil-based eDNA to detect the snail host and the schistosomiasis parasite in samples from Ekiran Village.
2. eDNA was found to be stable and detectable in soil up to 2.5 meters from watercourse banks. This capability is crucial for accurately mapping schistosomiasis transmission risk areas, a key action for achieving the targets of SDG 3.
3. As a non-invasive monitoring technique, this approach aligns with the conservation principles of SDG 14 (Life Below Water) and SDG 15 (Life on Land) by assessing species presence without disturbing natural habitats.

Comparative Analysis of Detection Methodologies

• Superior Sensitivity: The eDNA system consistently outperformed traditional malacological surveys. In Phase 2, eDNA detected O. h. quadrasi in 50% of positive sites and S. japonicum in 100% of positive sites that were missed by direct observation.
• Enhanced Surveillance: This heightened sensitivity allows for the identification of previously unknown transmission foci, which is critical for effective disease control and progressing towards the elimination targets outlined in SDG 3.
• High Agreement: Despite variations in detection rates between study phases, a high agreement (90%) between eDNA and malacological surveys in the broader Phase 2 sampling confirms the reliability of eDNA as a surveillance tool.

Technological Innovation and Contribution to SDG 9

• The study validated the use of digital PCR (dPCR) for the absolute quantification of eDNA, successfully detecting concentrations as low as one copy per microliter.
• This application of a novel molecular tool represents a significant technological advancement in eco-epidemiological surveillance, directly contributing to SDG 9 (Industry, Innovation, and Infrastructure) by leveraging scientific innovation for public health infrastructure.

Ecological Factors and Distribution Patterns: Informing Sustainable Interventions

Influence of Environmental Variables

• Soil pH was identified as a significant factor influencing eDNA detection. Understanding such environmental parameters is essential for optimizing sampling strategies and managing ecosystems to mitigate disease transmission, thereby supporting both SDG 15 and SDG 6.
• The distribution of eDNA was concentrated near watercourses, confirming the known habitat preferences of the snail host. This spatial data is invaluable for targeting interventions, making public health efforts more efficient and contributing to the development of safe and resilient communities under SDG 11 (Sustainable Cities and Communities).

Implications for Schistosomiasis Control and Broader SDG Achievement

Enhancing Disease Surveillance Frameworks for SDG 3

1. The soil-based eDNA system is a practical and highly sensitive tool that can complement or surpass traditional methods, especially for detecting amphibious snails in low-density populations.
2. Its ability to provide robust epidemiological data strengthens risk assessment, allowing for targeted public health responses, particularly after environmental disturbances like floods, which can alter disease vector distribution.
3. Integrating this system into national surveillance programs can accelerate progress towards the control and elimination of schistosomiasis, a key target of SDG 3.

Limitations and Future Directions for Sustainable Application

• Challenges: Current limitations include the need for specialized equipment, trained personnel, and high costs, which may hinder immediate adoption in resource-constrained areas. Environmental inhibitors in soil also pose a technical challenge.
• Opportunities for Innovation (SDG 9): Future research should focus on refining protocols to reduce costs, improve inhibitor resistance, and enhance accessibility. This continued innovation is vital for the sustainable application of the technology.
• Integrated Approach: To maximize impact, eDNA data should be integrated with ecological modeling and contextual data to create predictive risk maps. This holistic approach supports proactive public health management and builds community resilience, aligning with the principles of SDG 11.

1. Which SDGs are addressed or connected to the issues highlighted in the article?

SDG 3: Good Health and Well-being

• The article’s primary focus is on schistosomiasis, a parasitic disease affecting humans and animals. The study develops a sensitive detection method for the parasite (Schistosoma japonicum) and its snail host (Oncomelania hupensis quadrasi) to “identify schistosomiasis transmission risk areas – a crucial information to mitigate human and animal exposure.” This directly contributes to preventing and controlling a significant communicable disease.

SDG 6: Clean Water and Sanitation

• Schistosomiasis is a water-borne disease transmitted via freshwater snails. The study is conducted in and around “watercourses” and “waterway banks.” The detection of the parasite’s eDNA in these environments is an indicator of biological contamination of water resources, which poses a direct threat to public health and relates to the overall quality and safety of water bodies.

SDG 9: Industry, Innovation, and Infrastructure

• The research demonstrates a “novel approach” by applying a “soil-based eDNA detection system” using advanced technologies like dPCR. The article highlights that this innovative method is more sensitive than traditional surveys, stating it “can complement or even surpass the traditional method.” This represents an advancement in scientific research and technological capability for public health surveillance.

SDG 15: Life on Land

• The study investigates the presence and distribution of organisms within a specific terrestrial and freshwater ecosystem. It analyzes the “habitat preferences of O. h. quadrasi, which thrives in moist environments” and examines edaphic factors like soil pH. The eDNA method serves as a non-invasive tool for monitoring species within their natural habitats, contributing to a better understanding and management of inland ecosystems to control disease vectors.

2. What specific targets under those SDGs can be identified based on the article’s content?

Under SDG 3: Good Health and Well-being

• Target 3.3: By 2030, end the epidemics of AIDS, tuberculosis, malaria and neglected tropical diseases and combat hepatitis, water-borne diseases and other communicable diseases.
  
  The article directly addresses this target by focusing on schistosomiasis, a neglected tropical disease. The developed eDNA system is presented as a tool to “monitor schistosomiasis in areas with zero transmission, regions nearing elimination, and potential new endemic areas,” which is essential for disease control and elimination efforts.

Under SDG 6: Clean Water and Sanitation

• Target 6.6: By 2020, protect and restore water-related ecosystems, including mountains, forests, wetlands, rivers, aquifers and lakes.
  
  The research provides a method for monitoring the biological health of water-related ecosystems (watercourses and adjacent banks). By detecting the presence of a parasite and its intermediate host, the tool helps identify environmental health risks within these ecosystems, which is a prerequisite for their protection and management.

Under SDG 9: Industry, Innovation, and Infrastructure

• Target 9.5: Enhance scientific research, upgrade the technological capabilities of industrial sectors in all countries… encouraging innovation.
  
  This study is a clear example of enhancing scientific research to create innovative solutions. It describes the development, optimization, and application of a new surveillance technology (soil-based eDNA detection). The article notes its advantages, stating it “offers a valuable tool for identifying high-risk areas,” thereby upgrading the technological tools available for public health.

Under SDG 15: Life on Land

• Target 15.1: By 2020, ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services…
  
  The article contributes to the sustainable management of inland freshwater ecosystems by providing a tool to monitor disease vectors. Understanding the “distribution pattern of O. h. quadrasi and S. japonicum eDNA” helps in managing these environments to reduce disease transmission risks for local communities who rely on them.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

For Target 3.3 (End epidemics of neglected tropical diseases)

• The article provides a direct method for measuring the presence and distribution of the disease agent and its vector. The eDNA detection rates for S. japonicum and O. h. quadrasi serve as a proxy indicator for disease risk in a specific area. For example, the study reports detection rates of “20% (6/30) and 10% (3/30)” for the snail and parasite, respectively, in Phase 2. Tracking these rates over time can measure the effectiveness of intervention and control programs.

For Target 6.6 (Protect water-related ecosystems)

• The presence of S. japonicum eDNA in soil samples from waterway banks is an implicit indicator of the biological contamination of that water body. The quantification of eDNA, as mentioned in the article (“detected the presence of eDNA in as low as one copy per μl”), can be used as a measurable indicator of the level of contamination in the ecosystem, reflecting its health and safety for human use.

For Target 9.5 (Enhance scientific research and innovation)

• The article provides a clear performance indicator for the new technology by comparing its sensitivity to traditional methods. The finding that “50% (3/6) of O. h. quadrasi and 100% (3/3) of S. japonicum eDNA-positive sites in Phase 2 were not identified by malacological surveys” serves as a powerful indicator of the innovation’s improved capability and effectiveness. The higher detection rates of the eDNA method compared to the malacological survey is a quantifiable measure of technological advancement.

For Target 15.1 (Sustainable use of terrestrial and inland freshwater ecosystems)

• The study uses the spatial mapping of eDNA detections to understand the distribution of the snail host, noting that detections were “concentrated in areas near watercourses with a continuous water supply.” This spatial data on the presence of a key species acts as an indicator for identifying specific microhabitats that require targeted management within the broader ecosystem to ensure its safe and sustainable use.

4. Summary Table of SDGs, Targets, and Indicators

Source: idpjournal.biomedcentral.com