Babesia, also called Nuttallia, is an apicomplexan parasite that infects red blood cells and is transmitted by ticks. Originally discovered by the Romanian bacteriologist Victor BabeČ™ in 1888, over 100 species of Babesia have since been identified. Babesia comprises more than 100 species of tick-borne parasites that infect erythrocytes (red blood cells) in many vertebrate hosts.