Pathogen Exposure Assessment

Quantifying how people are exposed to fecal contamination through multiple environmental pathways—water, food, soil, surfaces, and drains.

Key Questions

  • What are the primary exposure pathways in urban settings?
  • Which populations face the highest exposure risks?
  • How do seasonal variations affect contamination levels?
  • What interventions most effectively reduce exposure?

Our Approach

The SaniPath (Sanitation Pathway Exposure Assessment) tool measures E. coli concentrations across multiple environmental samples—drinking water, stored water, street food, soil, drains, surface water, and hands. Combined with behavioral surveys documenting contact frequency, this data estimates population-level exposure risks and identifies high-priority intervention targets.

Active Projects

SaniPath Food Safety and Hygiene Assessment in four municipalities (field data collection complete)

Climate-Resilient Sanitation Study in flood-prone Paikgacha, Khulna (field work completed)

SaniPath assessment in Tanga City (field work complete)

In Bangladesh, PROMISE research revealed alarming contamination levels:

  • 80% of environmental samples contaminated with E. coli
  • 100% of floodwater, raw produce, and surface water samples positive
  • 72% of children and 69% of adults use surface water more than 10 times monthly
  • High exposure through contaminated drinking water and street food

In Ghana, the study found:

  • High knowledge (99% recognize handwashing prevents disease) but inconsistent practice (only 89% practice before cooking)
  • 80% rely on street food, though 55% believe it only “sometimes safe”
  • 87% aware of foodborne illness risks but 85% dissatisfied with vendor hygiene
  • 65% observed no hygiene messaging in markets

A Memorandum of Understanding between PROMISE-Bangladesh partners and WaterAid Bangladesh ensures that findings will inform planned sanitation investments, prioritizing climate-resilient containment systems, flood-resistant water sources, community-based water treatment, and food safety interventions.

Ghana’s Ministry of Local Government, Chieftaincy and Religious Affairs engaged PROMISE researchers to contribute findings to the revision of Standard Operating Procedures for Environmental Health Officers, with updated procedures expected in 2025 and national rollout training beginning in 2026.

  1. Wang Y, Mairinger W, Raj SJ, et al. (2022). Quantitative assessment of exposure to fecal contamination in urban environment across nine cities. Science of the Total Environment.
  2. Raj SJ, Wang Y, Yakubu H, et al. (2020). The SaniPath Exposure Assessment Tool: A quantitative approach. PLoS One.
  3. Amin N, Rahman M, Raj S, et al. (2019). Quantitative assessment of fecal contamination in Dhaka, Bangladesh using SaniPath. PLoS One.
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