* The microscopic agglutination test (MAT) is the gold standard serologic test for definitively diagnosing leptospirosis.
* The MAT detects antibodies produced by the immune system in response to the Leptospira bacteria.
* If there is a response, the antibodies will agglutinate and clump together when exposed to killed Leptospira bacteria.
* The test is performed by incubating a dilution series of the patient's serum with suspensions of different Leptospira serovars.
* If the patient's serum contains antibodies against a particular serovar, the antibodies will bind to the bacteria and cause them to agglutinate.
* The titer of the serum is the highest dilution that causes agglutination.
ELISA (Enzyme-linked immunosorbent assay)
* ELISA detects the presence of antibodies to various strains of Leptospira in the patient’s serum.
Polymerase chain reaction (PCR)
* PCR detects the genetic material of Leptospira in a patient’s blood, urine or cerebrospinal fluid (CSF).
* This technique is particularly helpful in diagnosing leptospirosis in patients who have not yet developed antibodies to the bacteria.
Rapid diagnostic tests
* Rapid diagnostic tests (RDTs) are used in outbreak settings.
* These tests detect the presence of antigens or antibodies specific for a Leptospira species in blood, urine or cerebrospinal fluid (CSF).
* The RDTs are simple to use, fast and cost-effective but they are usually not as sensitive or specific as the microscopic agglutination test or PCR.