Relative quantity of <i>Babesia</i> in lions sampled each year in the Serengeti (blue triangles) and Ngorongoro Crater (red circles) as determined by real-time PCR.

<p>Fatal outbreaks are highlighted in light red. Data are separated according to changes in sample preparation affecting levels of PCR product: (A) red blood cell pellets were extracted from all samples collected in 1984–1996, while (B) whole blood was collected for all subsequent samples. The relative quantity of hemoparasite DNA was calculated as average threshold PCR cycle divided by hemoglobin concentration and expressed as the fold difference greater than the sample with the smallest quantity of hemoparasite DNA. Levels of <i>Babesia</i> infection were significantly higher during the fatal outbreaks, in the Crater, and in assays performed on whole blood (all three factors significant at P<0.0001 in a multivariate analysis, <i>n</i> = 344).