Detection of Leishmania infantum by cytocentrifugation in peripheral blood from Leishmania positive PCR dogs

The veterinary guidelines for blood transfusion suggest Leishmania infantum screening by PCR techniques among potential blood donors for evaluating the infection risk. The aim of the present study was to investigate whether circulating amastigotes in peripheral blood may be detected using a cytocentrifugation technique in dogs with Leishmania infection confirmed by blood nested-PCR. For that, 20 untreated positive blood n-PCR dogs with serum anti-Leishmania antibodies (evidenced by IFAT) were included in this study, clinically examined and some conventional haematological and biochemical parameters were also determined leading to classify dogs into symptomatic (at least 3 anomalies, n = 6), oligosymptomatic (1 to 3 anomalies, n = 9) and asymptomatic (no detected anomaly, n = 5) groups. Prevalence of amastigotes determined by cytocentrifugation, mainly located into neutrophils, was 50% and 1 to 3 parasites by cytospot were evidenced in 3 symptomatic, 4 oligosymptomatic and in 3 asymptomatic dogs. In conclusion, blood n-PCR positive dogs reasonably harbour Leishmania organisms in peripheral blood and because asymptomatic n-PCR positive dogs have circulating amastigotes, the present study supports the recommendation to test and exclude n-PCR positive animals from blood donor programs.