Sir.—Babesiosis, a protozoal illness that is being diagnosed more frequently, is usually associated with fever, chills, hepatosplenomegaly, and signs of hemolysis, but can sometimes be seen as an asymptomatic infection.1 We recently treated two febrile infants who were infected with this parasite.
Patient Reports.—Patient 1.—A previously healthy 3-week-old girl from Southampton, NY, was seen for persistent fever following removal of a tick from her arm two weeks earlier. The child was admitted with a temperature of 40°C, irritability, and an enlarged spleen 3 cm below the costal margin. Her white blood cell (WBC) count was 11 700/mm3 (11.7×109/L), with 7% (0.07) polymorphonuclear leukocytes, 3% (0.03) band cells, 61% (0.61) lymphocytes, 26% (0.26) atypical lymphocytes, and 3% (0.03) monocytes. The hematocrit was 31% (0.31), the platelet count was 58 000/mm3 (58×109/L, and 6% of red blood cells (RBCs) had intracellular