Modeling the health impact of water and sanitation service deficits on waterborne disease transmission

Cholera is a waterborne disease that continues to pose serious public health
problems in many developing countries. Increasing water and sanitation coverage is
a goal for local authorities in these countries, as it can eliminate one of the root causes
of cholera transmission. The SIWDR (susceptible–infected–water–dumpsite–
recovered) model is proposed here to evaluate the effects of the improved coverage
of water and sanitation services in a community at risk of a cholera outbreak. This
paper provides a mathematical study of the dynamics of the water and sanitation
(WatSan) deficits and their public health impact in a community. The theoretical
analysis of the SIWDR model gave a certain threshold value (known as the basic
reproductive number and denoted R0) to stop the transmission of cholera. It was
found that the disease-free equilibrium was globally asymptotically stable whenever
R0 ≤ 1. The unique endemic equilibrium was globally asymptotically stable
whenever R0 > 1. Sensitivity analysis was performed to determine the relative
importance of model parameters to disease transmission and prevention. The
numerical simulation results, using realistic parameter values in describing cholera
transmission in Haiti, showed that improving the drinking water supply, wastewater
and sewage treatment, and solid waste disposal services would be effective strategies
for controlling the transmission pathways of this waterborne disease.