Leptospirosis is an under-diagnosed disease due to its protean clinical manifestations and due to the non-availability of acceptable antigen based tests. The incidence of the disease depends on the distribution of leptospirologists. Culture takes time as the organism is slow growing. Microscopic agglutination test (MAT), ELISA for IgM and IgG antibodies, Polymerase chain reaction (PCR) are done. There is controversy regarding the use of darkfield microscopy (DFM). Earlier workers reported pseudospirochaetes in blood. It is also believed that leptospires are seen in low concentration in blood and disappear after one week. Introduction of darkfield stop has reduced the usefulness of DFM to visualize spirochaetes. But microbiologists working with DFM have not noted this fact. This review article gives an update on the usefulness of DFM, MAT,ELISA and PCR in the early diagnosis of leptospirosis. Standardization of DFM and PCR could help in assessing the real burden of leptospirosis in the world.
