O OPOTA¹, Z BALMPOUZIS², C BERUTTO³, J KAISER-GUIGNARD⁴, G GREUB¹, J-D AUBERT², G PROD’HOM¹, O MANUEL⁵, K JATON<sup>1

1</sup>Institute of Microbiology, University Hospital of Lausanne, Lausanne, Switzerland, ²Pneumology Service, University Hospital of Lausanne, Lausanne, Switzerland, ³Transplantation Center, University Hospital of Lausanne, Lausanne, Switzerland, ⁴Hematology Service, University Hospital of Lausanne, Lausanne, Switzerland, ⁵Infectious Diseases Service, University Hospital of Lausanne, Lausanne, Switzerland

Background: Molecular diagnostic methods have significantly improved the diagnosis/management/treatments of viral infections in immunocompromised host. However, studies addressing their usefulness for the diagnostic of parasitic diseases, often delayed due to non-specific signs and symptoms, are lacking. We report the case of a lung transplant recipient in whom the diagnostic of visceral leishmaniasis (VL) could have been made months before symptoms appearance by the use of a Leishmania-specific PCR on peripheral blood (PB), suggesting a role of pre-emptive PCR-based diagnosis in transplant recipients.
Material/methods: We diagnosed a VL in a 61 y/o Swiss lung transplant recipient 12 months after the onset of chronic pancytopenia; parasite load already reached 8.9E+3 parasites per ml. We retrospectively tested the patients’ PB DNA samples collected after transplantation using a Leishmania specific real-time PCR targeting the 10,000 copies kinetoplastic DNA making it extremely sensitive (detection limit < 5.0E-4 parasites per ml).
Results: The first positive PCR (890 DNA copies/ml corresponding to less than 1 parasite/ml) occurred in a PB sample collected more than 6 months before the onset of pancytopenia, and 18 months before the diagnostic of VL. The parasite load regularly increased until the diagnostic of VL which occurred at a very high parasitic load (8.9E+7 DNA copies per ml; 8.9E+3 parasites per ml). The myelogram obtained 5 weeks before and initially negative by microscopy for parasites detection, was also positive by PCR (7.2E+5 DNA copies per ml). A 2 log decrease in DNA was observed 7 days after the initiation of the liposomal amphotericin B therapy and a monthly follow-up by PCR did not detect any parasite DNA at 6 months after discontinuation of amphotericin B.
Conclusions: This analysis demonstrates that using a Leishmania-specific real-time PCR on PB, parasite DNA can be detected long before the appearance of symptoms associated with VL in immunocompromised patients. This suggests the usefulness of pre-emptive PCR-based diagnosis on PB in SOT recipients at risk for developing VL, such as patients travelling and/or living in endemic areas.