Babesiosis

This chapter describes babesiosis as an emerging zoonotic disease caused by intraerythrocytic protozoa of the Apicomplexa phylum and transmitted by hard-bodied ticks. It reviews the first well-documented case of human Babesia infection, reported in 1957 in a splenectomized resident of Yugoslavia. Babesia spp. have been found to cause disease in humans; these include B. microti, B. duncani, and B. divergens-like spp. in North America, and B. divergens, B. microti and B. venatorum in Europe. Normally, humans are an uncommon and terminal host for Babesia spp., which depend on other species for their development and transmission. Ixodes scapularis is the primary vector of B. microti in the northeastern and upper midwestern United States. This tick also transmits Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis; Borrelia burgdorferi and Borrelia miyonii, etiologic agents of Lyme disease; Borrelia miyamotoi that causes relapsing fever, Powassan virus that causes encephalitis, and Ehrlichiosis muris-like infection.