Dipstick Assay for Serodiagnosis of Leptospirosis

An easy, rapid and robust dipstick assay for detection of leptospira-specific immunoglobulin M (IgM) antibodies was evaluated on 403 patients admitted for hospitalization because of fever. The clinical symptoms and signs of 35 patients were consistent with leptospirosis. The final diagnosis for the remaining patients was as follows: 136 with typhoid fever, 82 with hepatitis, 74 with malaria, 48 with infections of the respiratory tract, and 20 with fever of unknown origin. The clinical diagnosis of leptospirosis was confirmed for 24 (68.6%) patients by the combined results of the microscopic agglutination test (MAT), the reference test for leptospirosis, and of IgM ELISA, a standard laboratory test for the serodiagnosis of leptospirosis. In addition, serum specimens from 8 (2.2%) patients with a final clinical diagnosis other than leptospirosis were found to be positive in MAT and/or IgM ELISA. Compared with the results of MAT and IgM ELISA a sensitivity of 91.6% and specificity of 93.6% was calculated for the dipstick assay. Most of the serum samples from the laboratory confirmed patients gave a moderate to strong staining intensity of the antigen band of the dipstick and were easy to read. The results demonstrate that the dipstick assay is convenient to use and allows the rapid and accurate confirmation of patients with clinical suspicion of leptospirosis in areas where the disease is endemic. Correspondence: Dr Mochammad Hatta, Department Medical Microbiology, Faculty of Medicine, Hasanuddin University, Kampus Tamalanrea, Km 10, Makassar, Indonesia. Tel/Fax: 062-411-586971; E-mail : [email protected] SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH Vol 31 No. 3 September 2000 516 ficity since the presence of fibrin and protein in the urine samples can be mistaken for leptospires. We recently have developed an easy and robust dipstick assay, for the quick screening of patients with clinical suspicion of leptospirosis (Gussenhoven et al, 1997). The assay is aimed at the detection of Leptospira-specific immunoglobulin M (IgM) antibodies in serum samples. The highly stable ingredients allow the use of the assay under a wide range of conditions. Evaluation of the assay under different epidemiological and clinical conditions has demonstrated a high sensitivity, specificity and predictive values (Gussenhoven et al, 1997; Sehgal et al, 1999; Smits et al, 1999). The aim of this study was to determine the clinical utility of the test when applied in a hospital in a tropical country where the disease is endemic. MATERIALS AND METHODS