Babesia is an intracellular parasitic protozoan parasite on red blood cells of vertebrated hosts,belonging to the genus Babesia of the family Piroplasmidae,and is transmitted through tick biting,blood transfusions,organ transplant,and the maternal placenta.The clinical manifestations of human babesiosis vary widely,ranging from asymptomatic to fatal organ failure.Given the ongoing increases in global temperature and the continual expansion of the distribution ranges of medical vector species,human babesiosis is receiving increasing attention.This paper provides a review of the pathogenicity of Babesia during host and vector parasitism history.