What laboratory tests can be ordered to diagnose Leptospirosis?

From the Guidelines

To diagnose leptospirosis, you can order several laboratory tests, including Microscopic Agglutination Test (MAT), PCR testing of blood or urine, ELISA tests for IgM antibodies, and culture of blood, urine, or CSF, with the most recent and highest quality study 1 guiding the selection of these tests. When ordering lab tests for leptospirosis, it's essential to consider the timing of the illness, as the sensitivity of different tests varies throughout the course of the disease.

• During the first week of illness, PCR testing of blood or urine is highly sensitive, as it can detect the presence of Leptospira DNA before antibodies develop 1.
• In the later stages of infection, ELISA tests for IgM antibodies become more useful, as they can detect the immune response to the infection 1.
• The Microscopic Agglutination Test (MAT) is considered the gold standard for diagnosis, as it detects antibodies against Leptospira, but it may not be positive until later in the course of the illness 1. Other supportive tests, such as complete blood count (CBC), comprehensive metabolic panel (CMP), urinalysis, and coagulation studies, can help assess organ involvement and guide management. For optimal diagnosis, it's recommended to collect samples during both acute and convalescent phases (2-4 weeks apart) to demonstrate a fourfold rise in antibody titers, as suggested by the study 1. Early testing is crucial, as leptospirosis can progress rapidly, and prompt antibiotic treatment with doxycycline or penicillin significantly improves outcomes, highlighting the importance of timely and accurate diagnosis 1.

From the Research

Leptospirosis Lab Tests

The following lab tests can be ordered for the diagnosis of leptospirosis:

• Microscopic Agglutination Test (MAT) 2, 3, 4, 5
• IgM anti-Leptospira rapid diagnostic test (RDT) 2
• Polymerase Chain Reaction (PCR) targeting Lfb1 3
• IgM ELISA to Leptospira fainei serovar Hurstbridge 3
• IgM-ELISA (Serion-Virion) 4
• Immunochromatography test (Leptocheck-WB) 4
• SD Bioline Leptospira IgG/IgM 2
• Uji Leptospira IgM 2
• Fokus Leptospira 2
• Answer Leptospira 2

Characteristics of Leptospirosis Lab Tests

The characteristics of these lab tests are as follows:

• MAT: gold standard for leptospirosis diagnosis, high specificity, but requires specialized equipment and trained personnel 2, 3, 4, 5
• IgM anti-Leptospira RDT: rapid and easy to use, but may have lower sensitivity and specificity compared to MAT 2
• PCR: high sensitivity and specificity, but requires specialized equipment and trained personnel 3
• IgM ELISA: high sensitivity and specificity, but may have lower sensitivity compared to MAT 3, 4
• Immunochromatography test: rapid and easy to use, but may have lower sensitivity and specificity compared to MAT 4

Combination of Lab Tests

Combining two or more lab tests may improve diagnostic performance, as seen in the study by 2, which evaluated the combination of two RDTs. However, the choice of lab tests and their combination should be based on the specific clinical context and the availability of resources.