Clinical Laboratory Diagnosis of Human Leptospirosis

Context: Leptospirosis is a worldwide zoonotic infection which appears to be a re-emerging health problem. The clinical features of the disease are broad ranging, but are often similar to those of other infections. As a result, the accuracy of a clinical diagnosis of leptospirosis is low and confirmation requires the use of laboratory tests.Evidence Acquisition: The disease is usually diagnosed in the laboratory by different methods such as direct microscopy, culture, serological methods and molecular methods. The microscopic agglutination test (MAT) is considered the reference test among the several serological methods for leptospirosis diagnosis. However, isolation and identification of the microorganism allows for definitive diagnosis, and provides for epidemiological and prophylactic studies of this disease. Therefore, culture is a golden standard method. Polymerase chain reaction is a rapid, sensitive and specific means of detecting leptospiral infection, in contrast to serology tests. Further benefit is the ability to identify early infection especially during the first few days of the disease even before antibodies are detectable. Choice of test for diagnosis of leptospirosis depends on the stage of the disease. An ideal test will need to discriminate between leptospirosis and a broad spectrum of diseases that cause acute febrile illness and have overlapping clinical presentations. Although detection of antibodies is by itself no proof of a current infection, serological methods (such as MAT and ELISA) are often the most appropriate diagnostic methods.