Babesiosis.

A case of human babesiosis is presented. This case emphasizes the need to consider tick-borne disease in anyone who presents with prolonged and undulating fevers, chills, headache, myalgias, and arthralgias. This holds true particularly in areas endemic for tick-borne diseases, even in the absence of a history of tick bite. These symptoms, associated with signs of intravascular hemolysis, thrombocytopenia, and renal insufficiency in a patient who resides in, or with recent travel to, the Northeastern United States, strongly suggest a diagnosis of babesiosis.