Feasibility of the hydrogen sulfide test for the assessment of drinking water quality in post-earthquake Haiti

Abstract

In 2010 a magnitude 7.0 earthquake struck Haiti, severely damaging the drinking and waste water infrastructure and leaving millions homeless. Compounding this problem, the introduction of Vibrio cholera resulted in a massive cholera outbreak that infected over 700,000 people and threatened the safety of Haiti’s drinking water. To mitigate this public health crisis, non-government organizations installed thousands of wells to provide communities with safe drinking water. However, despite increased access, Haiti currently lacks the monitoring capacity to assure the microbial safety of any of its water resources. For these reasons, this study was designed to assess the feasibility of using a simple, low cost method to detect indicators of fecal contamination of drinking water that could be implemented at the community level. Water samples from 358 sources of drinking water in the Léogâne flood basin were screened with a commercially available hydrogen sulfide test and a standard membrane method for the enumeration of thermotolerant coliforms. When compared with the gold standard method, the hydrogen sulfide test had a sensitivity of 65% and a specificity of 93%. While the sensitivity of the assay increased at higher fecal coliform concentrations, it never exceeded 88%, even with fecal coliform concentrations greater than 100 colony forming units per 100 milliliters. While its simplicity makes the hydrogen sulfide test attractive for assessing water quality in low resource settings, the low sensitivity raises concerns about its use as the sole indicator of the presence or absence of fecal coliforms in individual or community water sources.