Optimized PCR using patient blood samples for diagnosis and follow-up of visceral leishmaniasis, with special reference to AIDS patients

We developed a highly sensitive PCR method that enables the diagnosis and p osttherapeutic follow-up of visceral leishmaniasis with patient blood. The PCR assay was thoroughly optimized by successive procedural refinements to increase its sensitivity and specificity. It was compared to in vitro culti vation as well as to direct examination of bone marrow and to serology. Two hundred thirty-seven patients presenting with clinical signs compatible wi th visceral leishmaniasis were included in the study. Thirty-six were diagn osed as having Mediterranean visceral leishmaniasis (MVL). Twenty-three of them, including 19 AIDS patients, were monitored during and after treatment over a period from 2 weeks to 3 years. Our PCR assay proved more sensitive than in vitro cultivation, direct examination, and seralogy for all patien ts. It is simple and can be adapted to routine hospital diagnostic procedur es. For the primary diagnosis of MVL, the sensitivity of PCR versus that of cultivation was 97 versus 55% with peripheral blood and 100 versus 81% wit h bone marrow samples. Regarding posttherapeutic follow-up, overall, 48% of positive samples were detected by PCR only, Seven patients presented with a clinical relapse during the study; six relapses were detected at first by PCR only, sometimes a few weeks before the reappearance of signs or sympto ms, We conclude that an optimized and well-mastered PCR assay with a periph eral blood sample is sufficient to provide a secure diagnosis far all immun ocompromised patients and most immunocompetent patients. We also suggest sy stematic posttherapeutic monitoring by PCR with peripheral blood for immuno compromised patients.