Prospective Evaluation of a Rapid Diagnostic Test Dot EIA (Typhidot) for Typhoid Fever

Abstract

Objective: A prospective evaluation of a rapid diagnostic test Dot EIA (Typhidot) for typhoid fever. Study design & duration: This prospective study was undertaken in a tertiary hospital from April 2007 to July 2008.
Research Methodology: The patients were divided into three groups as I, II & III with typhoid fever, typhoid suspects & non-typhoid febrile illnesses respectively. Blood culture and typhidot tests were done for the subjects included in the study. The validity of the typhidot test was evaluated by determ ining the sensitivity, specificity, positive and negative predictive value.
Results: The mean age in years was 28±19 (SD). Out of 150 subjects, males were more than females. The typhidot IgM yielded very high sensitivity, specificity and a negative predictive value noted in group I = 93% & 98.80% 93% respectively and in group II= 79%, 98.80%, & 83% respectively where as in group III (non-typhoid febrile controls), the IgM antibodies were not detected at all (p=0.01). Sensitivity, specificity, and negative predictive value for typhidot IgG noted in group I = 73%, 63%, & 22.4% respectively and in group II = 82%, 37%, & 68% respectively (p=0.03) and a false positive reading of 63% was noted in group III (controls).
Conclusions: Typhidot test is a valid tool in the diagnosis of typhoid fever but a reliable and valid interpretation should be based on positive IgM.