[Which screening for Leishmania infantum in asymptomatic blood donors?]

Leishmaniasis is a protozoan infection endemic in Italy with a greatly underestimated prevalence. The recent documentation of parasitaemia in blood donors is a cause of concern for blood safety. Because there is no screening against leishmania, we performed a study to assess the presence of protozoa in blood donors of Siena district (Tuscany) during the seasonal activity of the vector. From June to October 2007, 162 patients were screened for Leishmania infantum by indirect immunofluorescence serology (IFAT) and PCR for kinetoplast (kDNA). No subject was positive for antibodies, while 11 samples (6.8%) were positive for kDNA. A second PCR (nested-PCR) was negative for all kDNA positive individuals and other subjects for a total of 55 samples (33% of total subjects). The sequence analysis of three samples positive for kDNA was compatible with mitochondrial DNA. Through the techniques used, we were unable to confirm the presence of leishmania in the blood of the subjects studied. The choice of the diagnostic protocol in blood donors remains an open issue as molecular analysis (kDNA) seems to suggest, in our experience, limits of specificity.