Integrating disease control strategies: balancing water sanitation and hygiene interventions to reduce diarrheal disease burden

Abstract

Objectives: Although the burden of diarrheal disease resulting from inadequate water quality, sanitation practices, and hygiene remains high, there is little understanding of the integration of these environmental control strategies. We tested a modeling framework designed to capture the interdependent transmission pathways of enteric pathogens.

Methods: We developed a household-level stochastic model accounting for 5 different transmission pathways. We estimated disease preventable through water treatment by comparing 2 scenarios: all households fully exposed to contaminated drinking water and all households receiving the water quality intervention.

Results: We found that the benefits of a water quality intervention depend on sanitation and hygiene conditions. When sanitation conditions are poor, water quality improvements may have minimal impact regardless of amount of water contamination. If each transmission pathway alone is sufficient to maintain diarrheal disease, single-pathway interventions will have minimal benefit, and ultimately an intervention will be successful only if all sufficient pathways are eliminated. However, when 1 pathway is critical to maintaining the disease, public health efforts should focus on this critical pathway.

Conclusions: Our findings provide guidance in understanding how to best reduce and eliminate diarrheal disease through integrated control strategies.

FIGURE 1—

Diagram illustrating potential transmission routes for enteric (waterborne) pathogens (a) and how indirect exposure to contaminated drinking water can occur as a result of the multiple and interdependent nature of exposure pathways (b).

FIGURE 2—

Schematic for a household-level infection transmission model. Note. β_c = between-household transmission; β_d = within-household transmission; φ = contamination of water; β_dw = exposure from contaminated water; β_e = other sources.

FIGURE 3—

Contours of preventable fractions associated with improving water quality for different rates of household-level and community-level transmission. Note. Each contour plot involves a different contamination rate (φ): 0 (a), 0.5 (b), 1.0 (c), 1.5 (d), and 2.0 (e).