The use of latex agglutination for the diagnosis of acute human leptospirosis.

The authors evaluated a simple latex agglutination test for the serodiagnosis of acute human leptospirosis. A total of 380 serum samples from 85 confirmed leptospirosis patients and 202 non-leptospirosis patients were selected Using the selected cut-off value of weakly positive, the overall sensitivity and overall specificity of the test were 94.1% and 97.0% respectively. The weighted kappa value for agreement reading between two independent examiners was 0.82. When focused on the first sera obtained from the patients, the sensitivity of the test for acute infection sera was only 17.6%. The latex agglutination test is easy to perform with no need for training and no requirement of special equipment. The assay has a good sensitivity and specificity. This is an interesting alternative assay for serodiagnosis of acute human leptospirosis.

A prospective evaluation of four immunodiagnotic assays for human leptospirosis.

This was a prospective evaluation of four immunodiagnostic assays for human leptospirosis, including the indirect immunofluorescence test (IFA), the microscopic agglutination test (MAT), the LEPTO dipstick, and the latex agglutination (LA) test. Four hundred ninety-two serum samples were collected from 348 patients who presented with acute fever without localizing signs. The sensitivities of the IFA, MAT, Dipstick, and LA were 91.9, 76.6, 77.4, and 83.1%, respectively. The specificities of these assays were 100.0, 100.0, 89.3, and 83.5, respectively. Even though IFA showed the highest overall sensitivity and specificity, when acute sera were considered, the LA was the most sensitive (28.7%). All 3 genus specific antibody assays had broad reactivity against various serogroups. The MAT is best suited for the reference laboratory, where it can be maintained with the battery of live antigens; the IFA is suited for a laboratory with sophisticated equipment and technical expertise; the Dipstick and LA are suitable for peripheral laboratories which lack expensive equipment and expertise.

Evaluation of enzyme-linked immunosorbent assay and indirect hemagglutination assay for detection of leptospiral antibody by using three different antigens.

Evaluation of enzyme linked immunosorbent assay (ELISA) and indirect hemagglutination assay (IHA) for detection of leptospiral antibody were performed using three different soluble antigens extracted from Leptospira interrogans serovar Bataviae including heat extracted antigen (HEA), sonicated antigen (SA) and deoxycholate extracted antigen (DEA). One hundred seventy-eight sera from 85 confirmed leptospirosis cases and 202 non-leptospirosis cases were examined SA-IHA showed the highest sensitivity of 98.8% followed by SA-ELISA-IgM and DEA-ELISA-IgM which showed an equal sensitivity of 97.6%. SA-ELISA-IgM was the most specific (96.5%) test followed by DEA-ELISA-IgM and SA-IHA which gave an equal specificity of 94.1%. The IgG-ELISA tests were less sensitive and specific than the others. These data indicated that the IgG-ELISA tests were not suitable as diagnostic tests for acute leptospirosis in humans. Using acute phase sera the sensitivity of DEA-ELISA-IgM, SA-ELISA-IgM and HEA-ELISA-IgM were 22.4%, 20.0% and 20.0% respectively, while those of the IgG ELISA tests were 32.9%, 17.6% and 10.6% respectively, the sensitivity of SA-IHA and DEA-IHA were 22.4% and 10.6% respectively. In conclusion, both the IgM-ELISA tests using SA and DEA and the IHA using SA are not different in diagnosis of human leptospirosis. SA is the most suitable antigen for detection of leptospiral antibody by IgM ELISA and IHA.

The etiology of acute pyrexia of unknown origin in children after a flood.

Acute pyrexia of unknown origin (PUO) is a major public health problem in Thailand. We studied the etiology of 180 cases of acute PUO in children after a sudden severe flood in Hat Yai city in 2000. Dengue infection and leptospirosis accounted for more than half of the total cases. Dengue hemorrhagic fever was the most common (29.4%) followed by leptospirosis (27.2%) and scrub typhus infection (1.1%). Five serovars of leptospires were involved in this study. Leptospira interrogans bataviae was the most common (86.5%). Acute serum antibody testing could detect only 52.8% and 40.8% of dengue and leptospirosis cases, respectively. This study showed both should be included in the presumptive diagnosis of acute PUO in patients after flooding.