Abstract
Spirochete infections of birds are caused by helical-shaped bacteria of the order Spirochaetales, family Spirochaetaceae. Two distinct syndromes exist because of differences in spirochete colonization, pathogenesis, and lesion production; non-relapsing, tickbourne, acute septicemic borreliosis caused by Borrelia anserina; and subacute-to-chronic intestinal disorders of varying severity caused by a divese group of spirochetes of the genus Brachyspira.