Occurrence of Leishmania donovani parasitemia in plasma of infected hamsters

Intracardiac transfusion of plasma, mononuclear cell fraction and blood of infected hamster donors induced visceral leishmaniasis in normal hamster re ceptors. At the moment of transfusion, the donors already showed all the ty pical signs of the disease: ascites, cachexia, as well as splenomegaly and a high parasite load in the spleen and liver, All transfused hamsters devel oped typical visceral leishmaniasis between 90 and 120 days, indicating tha t all blood products were infectious. Transfusion of the mononuclear cell f raction induced the highest values of parasitic load (spleen, 766 Leishman Donovan Units (LDU); liver, 2650 LDU), splenomegaly and hepatomegaly (splee n -liver/body relative weight: 1.130 and 6.870, respectively). Animals that received the plasma fraction also developed visceral leishmaniasis, showin g similar parasitic load (spleen, 107 LDU; liver, 220 LDU) and spleen -live r/body relative weight (1.005 and 6.35, respectively) than those transfused with whole blood. The finding of typical Leishmania donovani infection in animals transfused with plasma demonstrates the possibility of the extracel lular location of parasites, free in this blood fraction deprived of red an d white blood cells. Fluorescence-assisted cell sorter analysis (FACS) of p lasma showed the presence of particles corresponding in size to amastigotes , which fluoresced strongly with the serum of a patient with Kala-azar (73% ), but not with normal serum. (C) 2001 Elsevier Science B.V. All rights res erved.