Identification of Ehrlichia in Human Tissue

To the Editor: In 1987, Maeda et al. reported a case of human ehrlichiosis diagnosed by the serologic response to Ehrlichia canis and ultrastructural identification of clusters of small bacteria in cytoplasmic vacuoles of peripheral-blood leukocytes.¹ Since that time more than 160 cases have been reported.^2,3 Although the clinical and epidemiologic description of human ehrlichiosis is increasingly well defined, there have been neither published reports of isolation of the agent from humans nor proof of the antigenic identity of the ehrlichia-like organisms in clinical specimens from humans. We recently used immunohistology to identify an organism antigenically related to E. canis.