Which lab tests are used to confirm a diagnosis of leptospirosis?

Updated: Jul 08, 2021
  • Author: Sandra G Gompf, MD, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Laboratory confirmation of leptospirosis can be accomplished through isolation of the pathogen or by serologic testing.

Isolation of the leptospires from human tissue or body fluids is the criterion standard, but culture is not routinely available; thus, molecular assays such as DNA PCR are more commonly used, if available. Consultation with the local microbiology laboratory is essential, because processing requires specialized techniques. Urine is the most reliable body fluid to study because the urine contains leptospires from the onset of clinical symptoms until at least the third week of infection.

Other body fluids contain the organism, but the window of opportunity to isolate them is shorter. Blood and CSF may produce positive PCR or cultures during the first 7-10 days of symptoms.

Tissues (ie, liver, muscle, kidney, skin, eyes) are also sources of identification of the leptospires but are obviously more complicated to acquire.

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