Simplified Protocols for Cholera Diagnosis in the National Public Health Laboratory, Port-au-Prince, Haiti

Abstract

While the incidence of cholera is decreasing in Haiti, the time required to render stool culture results with antibiogram using the standard method practiced at the National Public Health Laboratory (LNSP) remains at an average of 80 hours. This delay can be further lengthened by the process of rendering the analysis reports to the sites of care which significantly delays the community responses to cholera. Through this study, we have aimed to assess the reliability of partial results. We have studied 250 stool samples that were analyzed between January and September 2017 at the LNSP by determining the specificity, positive predictive value and positive likelihood ratio of i) the identification of yellowish colonies and ii) the identification of yellowish colonies with a positive oxidase assay in comparison to the stool culture. Compared to the entire process, the identification of yellowish colonies showed a specificity of 56%, a positive predictive value of 69% and a positive likelihood ratio of 2.27. The identification of yellowish colonies with a positive oxidase assay showed a specificity of 77%, a positive predictive value of 81% and a positive likelihood ratio of 4.31. The communication of partial results at these steps would likely guide community interventions despite a relative decrease in reliability of the results.