Abstract
The validity of avian species of Babesia is reviewed and 13 species recognized. Slides from records of Babesia in the literature have been re-examined and their status determined. Erroneous published records have been addressed. Previously regarded piroplasms of the genera Babesiosoma and Haemohormidium are reappraised and their relationship to Babesia and the Aegyptianella-Rickettsia group of organisms discussed. Host-specificity, pathogenicity and vectors are also discussed.