Experimental Babesia microti infection in golden hamsters: Immunoglobulin G response and recovery from severe hemolytic anemia

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We described the parasitemia, hematologic changes, and immunity developed by golden hamsters during 8 wk of infection with Babesia microti following experimental inoculation. All 8 hamsters used in this study were readily infected. Animals attained peak parasitemias asynchronously but within a 2-wk period. Most of the animals reached their peak parasitemia by 4 wk postinoculation, attaining a mean ± SD of 21.9 ± 9.4% infected erythrocytes (range = 20-35%). Red blood cell count, packed cell volume, and hemoglobin level were used to monitor the course of the hemolytic anemia experienced by infected hamsters. All 3 measures corresponded inversely to the parasitemia; significant hematologic changes (P = 0.0001) were observed during the 8 wk of monitoring. Although all hamsters suffered from severe hemolytic anemia, they also recovered within the same period. Golden hamsters developed a detectable anti-B. microti IgG response by 2 wk postinoculation. Individual animals typically attained peak antibody levels (≤1:8,192) 1 wk after the peak parasitemia. Hamsters retained a high IgG titer (≤1:4,096), although parasitemias fell dramatically, fluctuating thereafter at low levels (<5%).

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Journal of Parasitology