International Multicenter Evaluation of the Clinical Utility of a Dipstick Assay for Detection of Leptospira -Specific Immunoglobulin M Antibodies in Human Serum Specimens

Abstract

We performed a multicenter evaluation of a robust and easily performed dipstick assay for the serodiagnosis of human leptospirosis. The assay is aimed at the detection of Leptospira-specific immunoglobulin M (IgM) antibodies. The study involved 2,665 serum samples collected from 2,057 patients with suspected leptospirosis in 12 countries on five continents with different levels of endemicity and different surveillance systems. The patients were grouped as laboratory-confirmed leptospirosis case patients and noncase patients based on the results of culturing and the microscopic agglutination test. Paired samples from 27.7% of the subjects were tested. Of the 485 case patients, 87.4% had a positive dipstick result for one or more samples. Of the 1,513 noncase patients, only 7.2% had a positive result. Whereas most (88.4%) of the positive samples from the case patients showed moderate to strong (2+ to 4+) staining in the dipstick assay, most (68.1%) of the positive samples from the noncase patients showed weak (1+) staining. The sensitivity of the dipstick assay increased from 60.1% for acute-phase serum samples to 87.4% for convalescent-phase samples. The specificities for these two groups of samples were 94.1 and 92.7%, respectively. The dipstick assay detected a broad variety of serogroups. The results of the dipstick assay were concordant (observed agreement, 93.2%; kappa value, 0.76) with the results of an enzyme-linked immunosorbent assay for the detection of specific IgM antibodies, a test which is often used in the laboratory diagnosis of current or recent leptospirosis. This study demonstrated that this easily performed dipstick assay is a valuable and useful test for the quick screening for leptospirosis; has a wide applicability in different countries with different degrees of endemicity; can be used at all levels of the health care system, including the field; and will be useful for detecting and monitoring outbreaks of leptospirosis.

Simple Latex Agglutination Assay for Rapid Serodiagnosis of Human Leptospirosis

“…The results of the latex agglutination assay for the four study groups combined showed 89.4% agreement (kappa, 0.63; 95% confidence interval [CI], 0.57 to 0.69) with the results of the MAT, 95.2% agreement (kappa, 0.81; 95% CI, 0.75 to 0.87) with the results of the IgM ELISA, and 93.4% agreement (kappa, 0.74; 95% CI, 0.68 to 0.80) with the results of a dipstick assay for the detection of Leptospira-specific IgM antibodies, which we described previously (5,10,11,16). The sensitivity of the latex agglutination assay was somewhat lower than the sensitivity of the IgM ELISA, the specificity and positive predictive value were significant lower, and the negative predictive value was the same ( Table 2).…”

Latex based, rapid and easy assay for human leptospirosis in a single test format

“…In these circumstances relatively simple assays such as the haemagglutination assay (Levett & Whittington 1998) may be used, but this assay has a limited sensitivity for samples collected early in the disease (Ef¯er et al 2000). Stability of assay reagents is an important prerequisite for tests used in tropical countries, and we recently described a dipstick assay (Gussenhoven et al 1997;Smits et al 1999;2000) and a latex agglutination test (Smit et al 2000b) for the detection of Leptospira-speci®c antibodies in human sera. The latex agglutination assay is performed by mixing on an agglutination card 5 ll serum with 5 ll antigen-coated, dyed latex beads.…”

“…Stability of assay reagents is an important prerequisite for tests used in tropical countries, and we recently described a dipstick assay ( Gussenhoven et al . 1997 ; Smits et al . 1999 , 2000) and a latex agglutination test ( Smits et al .…”

Validation of a Microsphere Immunoassay for Serological Leptospirosis Diagnosis in Human Serum by Comparison to the Current Gold Standard

“…If the stage of the disease is unknown, both acute and immune phase tests are performed. Other serological test methods have previously been developed including flow cytometry [ 10 ], complement fixation testing [ 11 ], indirect hemagglutination assay [ 12 ] an IgM dipstick assay [ 13 ] and an IgM enzyme-linked immunosorbent assay (ELISA) in a number of formats [ 14 , 15 ]. Each of these assays has its advantages and disadvantages [ 16 ] and the type of assay used for diagnosis is generally dependant on the facilities available.…”