Babesia microti infection and hemophagocytic lymphohistiocytosis in an immunocompetent patient.

Babesiosis is a rare and potentially severe tick-borne illness endemic to the Northeastern and upper Midwestern regions of the USA. Hemophagocytic lymphohistiocytosis is an uncommon condition resulting from over-activation of the immune system. The first known case of babesiosis and hemophagocytic lymphohistiocytosis in an immunocompetent patient is reported here.