Evaluation of the clinical utility of a rapid blood test for human leptospirosis

A rapid assay device for the detection of Leptospira-specific immunoglobulin M (IgM) antibodies was applied on whole blood samples collected from a group of consecutive patients admitted with clinical suspicion of leptospirosis to a district hospital in Kerala, India. The hospital is located in an area that is endemic for leptospirosis. The results of the rapid assay showed an agreement of 94.3% with those of an IgM ELISA routinely used for the serodiagnosis of leptospirosis. The rapid assay was simply performed by the addition of 10 microL blood to the sample well of a plastic assay device followed by the addition of 130 microL sample fluid. The assay was read after 10 min by visual inspection and was scored positive when staining of the antigen line in the test zone was observed. The assay utilizes stabilised components and can be stored without the need for refrigeration. These characteristics make the assay ideal in areas where the disease is common and where laboratory support is not routinely available.