Babesiosis, caused by infection with intraerythrocytic parasites of the genus Babesia, is one of the most common infections of free-living animals worldwide and is gaining increasing interest as an emerging zoonosis in humans. Although capable of infecting a wide range of vertebrates, babesial parasites require both a competent vertebrate and nonvertebrate host to maintain transmission cycles. All babesial parasites described to date are transmitted by ixodid ticks to their vertebrate hosts. The parasites replicate in the vertebrate hosts’ red blood cells and are called piroplasms due to their pear-shaped appearance when within the infected host cells (99, 226).