Babesiosis: problems in diagnosis using autoanalyzers

A 76-year-old white man previous diagnosed as having Waldenstrom's macroglobulinemia continued with persistent fevers and sweats for two and a half years. Recently, repeated automated differentials during 11 days of hospitalization failed to note any intracellular inclusions in the RBCs. Blood sent to the Microbiology Laboratory was noted to contain Babesia species. A review of the hematology slides revealed that Babesia species was present on all the slides the analyzer had screened. This failure to note infected RBCs may pose serious diagnostic problems.