Figure 3. Boxplots of infection intensity across ameba species after experimental infection with Yersinia pestis. Infection intensity frequencies followed a strong negative binomial distribution. Median infection intensities (horizontal lines inside boxes): AC = 3, AL = 4, AP = 3, DD = 2, VV = 1. Red diamonds denote mean infection intensity (Table). Each ameba species had several high-intensity outliers ranging up to a maximum of 84 intracellular bacteria observed in 1 A. lenticulata ameba (note broken y-axis). AC, Acanthamoeba castellanii (n = 1,441); AL, A. lenticulata (n = 1,156); AP, A. polyphaga (n = 737); DD, Dictyostelium discoideum (n = 624); VV, Vermamoeba vermiformis (n = 528).