Diagnostic reliability of an immunochromatographic test for Chagas disease screening at a primary health care centre in a rural endemic area

Many patients with Chagas disease live in remote communities that lack both equipmentand trained personnel to perform a diagnosis by conventional serology (CS). Thus,reliable tests suitable for use under difficult conditions are required. In thisstudy, we evaluated the ability of personnel with and without laboratory skills toperform immunochromatographic (IC) tests to detect Chagas disease at a primary healthcare centre (PHCC). We examined whole blood samples from 241 patients and serumsamples from 238 patients. Then, we calculated the percentage of overall agreement(POA) between the two groups of operators for the sensitivity (S), specificity (Sp)and positive (PPV) and negative (NPV) predictive values of IC tests compared to CStests. We also evaluated the level of agreement between ELISAs and indirecthaemagglutination (IHA) tests. The readings of the IC test results showed 100%agreement (POA = 1). The IC test on whole blood showed the following values: S =87.3%; Sp = 98.8%; PPV = 96.9% and NPV = 95.9%. Additionally, the IC test on serumdisplayed the following results: S = 95.7%; Sp = 100%; PPV = 100% and NPV = 98.2%.Using whole blood, the agreement with ELISA was 96.3% and the agreement with IHA was94.1%. Using serum, the agreement with ELISA was 97.8% and the agreement with IHA was96.6%. The IC test performance with serum samples was excellent and demonstrated itsusefulness in a PHCC with minimal equipment. If the IC test S value and NPV withwhole blood are improved, then this test could also be used in areas lackinglaboratories or specialised personnel.