Title: 

The joint effects of efficacy and compliance: a study of household water treatment effectiveness against childhood diarrhea

Year of Publication:

2013

Authors:

Enger, KS, Nelson, KL, Rose, JB, Eisenberg, JNS

Journal:

Water research

Abstract:

The effectiveness of household water treatment ({HWT)} at reducing diarrheal disease is related to the efficacy of the {HWT} method at removing pathogens, how people comply with {HWT}, and the relative contributions of other pathogen exposure routes. We define compliance with {HWT} as the proportion of drinking water treated by a community. Although many {HWT} methods are efficacious at removing or inactivating pathogens, their effectiveness within actual communities is decreased by imperfect compliance. However, the quantitative relationship between compliance and effectiveness is poorly understood. To assess the effectiveness of {HWT} on childhood diarrhea incidence via drinking water for three pathogen types (bacterial, viral, and protozoan), we developed a quantitative microbial risk assessment ({QMRA)} model. We examined the relationship between log(10) removal values ({LRVs)} and compliance with {HWT} for scenarios varying by: baseline incidence of diarrhea; etiologic fraction of diarrhea by pathogen type; pattern of compliance within a community; and size of contamination spikes in source water. Benefits from increasing {LRVs} strongly depend on compliance. For perfect compliance, diarrheal incidence decreases as {LRVs} increase. However, if compliance is incomplete, there are diminishing returns from increasing {LRVs} in most of the scenarios we considered. Higher {LRVs} are more beneficial if: contamination spikes are large; contamination levels are generally high; or some people comply perfectly. The effectiveness of {HWT} interventions at the community level may be limited by imperfect compliance, such that the benefits of high {LRVs} are not realized. Compliance with {HWT} should be carefully measured during {HWT} field studies and {HWT} dissemination programs. Studies of pathogen concentrations in a variety of developing-country source waters are also needed. Guidelines are needed for measuring and promoting compliance with {HWT.}

URL:

https://doi.org/10.1016/j.watres.2012.11.034