A brief review on the laboratory diagnosis of leptospirosis.

Leptospirosis is a ubiquitous zoonotic disease that may be maintained in either wild or domesticated animal species. These bacteria have been classified into serovars based on their antigenic characteristics and, more recently, into species based on genomic studies. They produce both chronic and acute infections. Chronic infections of serovars in the host species to which they have become adapted can result in long term shedding, providing a source of acute infection for other species. As clinical presentation can vary greatly, diagnosis often depends on laboratory methods. In addition to diagnostic testing, herd health monitoring and screening for international trade purposes are performed at veterinary laboratories. The test method selected varies depending on the samples available and the purpose of testing. An increasing variety of laboratory methods are being described for detection of bacteria and antibodies. In addition to classical methods such as culture, dark-field, microscopy and the microscopic agglutination test (MAT), a variety of polymerase chain reaction (PCR), indirect enzyme-linked immunosorbent assay (ELISA), competitive ELISA and other rapid serological tests have been described. This review describes the advantages and limitations of these assays together with other factors that may affect results and their interpretation, such as species variation, vaccination and antibiotic administration.