While taking a day cruise to Block Island, your brother is bitten by a deer tick, the same vector that carries Borrelia burgdorferi. He did not realize that the tick was on him until approximately 72 hrs later, at which time he yanked it off of his skin and flushed it down the toilet. Several days later, he developed a high fever, headache and muscle pain. When he went to see the doctor, he was told that he was severely anemic and his liver function was 75% of normal. A blood smear showed small protozoan parasites within your brother’s red blood cells—similar to the malarial parasite. The doctor prescribes chloroquine and tells your brother that it is a good thing that he still has his spleen. What did your brother have and what is the causative agent?