EXPERIMENTAL BABESIA-MICROTI INFECTION IN GOLDEN-HAMSTERS - IMMUNOGLOBULIN-G RESPONSE AND RECOVERY FROM SEVERE HEMOLYTIC-ANEMIA

We described the parasitemia, hematologic changes, and immunity develo ped by golden hamsters during 8 wk of infection with Babesia microti f ollowing experimental inoculation. All 8 hamsters used in this study w ere readily infected. Animals attained peak parasitemias asynchronousl y but within a 2-wk period. Most of the animals reached their peak par asitemia by 4 wk postinoculation, attaining a mean +/- SD of 21.9 +/- 9.4% infected erythrocytes (range = 20 - 35%). Red blood cell count, p acked cell volume, and hemoglobin level were used to monitor the cours e of the hemolytic anemia experienced by infected hamsters. All 3 meas ures corresponded inversely to the parasitemia; significant hematologi c changes (P = 0.0001) were observed during the 8 wk of monitoring. Al though all hamsters suffered from severe hemolytic anemia, they also r ecovered within the same period. Golden hamsters developed a detectabl e anti-B. microti IgG response by 2 wk postinoculation. Individual ani mals typically attained peak antibody levels (greater than or equal to 1:8,192) 1 wk after the peak parasitemia. Hamsters retained a high Ig G titer (greater than or equal to 1:4,096), although parasitemias fell dramatically, fluctuating thereafter at low levels (< 5%).