show Abstracthide AbstractBabesia species are tick-transmitted pathogens and causative agents of babesiosis, a malaria-like disease of major medical and veterinary importance. Of the different species of Babesia that infect humans, Babesia duncani causes severe infection in patients, is lethal in immunocompetent mice and hamsters. Studies using a newly developed in vitro culture system for B. duncani in human red blood cells revealed that the parasite is inherently less susceptible to drugs recommended for therapy of human babesiosis. Equally important, despite the highly virulent nature of this parasite and the risk it may pose as an emerging pathogen, little is known about its biology and pathogenesis. To this end, we completed the first assembly and annotation of the nuclear genome of this parasite.