Babesia (also called Nuttallia) is a genus of protozoan apicomplexan piroplasms which was discovered by the Romanian bacteriologist Victor Babeș, that infect the blood and cause a parasitic, hemolytic disease known as babesiosis. Over 100 species of Babesia have been identified, but only a few have been documented to be pathogenic in humans.In the United States, B. microti is the most common strain associated with humans. Other species infect cattle, livestock, and occasionally domestic animals. People who contract babesiosis suffer from malaria-like symptoms. As a result, malaria is a common misdiagnosis for the disease.