Enlargement of the spleen and parasitemia during the acute phase of <i>B. microti</i> infection.

<p>For the infection, 200 ml of an infected blood suspension (representing 20% parasitemia) was injected intraperitoneally. Control mice were injected with an equal total number of uninfected cells. (A) Enlargement and mean weight of spleens from <i>B. microti</i>-infected mice. (B) Identification of parasitized erythrocytes using Wright-Giemsa-stained blood smears (left panel) and the frequency of erythrocytes infected with <i>B. microti</i> versus the total number of red blood cells (right panel). Representative gel showing the PCR amplication of <i>B. microti</i>-specific 18S ribosomal ribonucleic acid genes (229 base pair segment) for the efficient detection of <i>B. microti</i> infection. Lane 1, negative genomic DNA control; Lane 2, positive control; Lane 3, day 7 after infection; Lane 4, day 11 after infection; Lane 5, day 14 after infection; Lane M, DNA ladder marker. All results represent at least five independent experiments with five mice in each group.