What is the role of polymerase chain reaction (PCR) in the workup of leishmaniasis?

Updated: Feb 18, 2020
  • Author: Craig G Stark, MD, FACP, FFTM, RCPS(Glasg), FISTM; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Answer

Over the past several years, significant advances in polymerase chain reaction (PCR) techniques have allowed for the highly sensitive and rapid diagnosis of specific Leishmania species. PCR can identify parasite DNA using sequences from the variable region of kinetoplast DNA. [23] However, a negative serologic test result does not exclude the possibility of a leishmanial infection.

Although currently limited to military and reference laboratories, leishmanial PCR diagnosis is becoming more widely available in developing-world laboratories and field sites. [24, 25] Even in remote locations and under harsh conditions, this technique has proven its worth, as evidenced by the US military's experience with Leishmania infection in Iraq.

Validated genus-specific PCR primers exist, and approval of this assay by the US Food and Drug Administration (FDA) has been sought so that it can be used in worldwide facilities certified by the College of American Pathologists (CAP). Species-specific PCR probes allow for rapid speciation in confirmed cases of leishmaniasis, and some are undergoing final validation.

Note: Although many laboratories worldwide offer species-level PCR diagnostics, few have undergone the scientific rigor of complete validation necessary to assure accuracy of these species diagnostics. Many of these assays are suspect and may be misleading.

Consequently, in the United States, FDA approval of these assays should be sought, or the assays should be performed in certified laboratories in order to be confident of the results. Difficult cases should be referred to reference laboratories in the United States for rapid diagnosis and speciation, such as the Walter Reed Army Institute of Research Leishmania Diagnostic Laboratory or the Leishmania Diagnostic Laboratory at the US Centers for Disease Control and Prevention (CDC).


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