Babesia (also called Nuttallia) is an Apicomplexan parasite that infects red blood cells, transmitted by ticks. Originally discovered by the Romanian bacteriologist Victor Babeș, over 100 species of Babesia have since been identified.
Babesia species infect livestock worldwide, wild and domestic vertebrate animals and occasionally humans where it causes the disease babesiosis. In the United States, B. microti is the most common strain of the few which have been documented to cause disease in humans. (see Wikipedia)
Babesia is one of the many components of lyme disease.