eubacteria, eubacterium, true bacteria - a large group of bacteria having rigid cell walls; motile types have flagella

order Spirochaetales, Spirochaetales - higher bacteria; slender spiral rodlike forms

treponema - spirochete that causes disease in humans (e.g. syphilis and yaws)

borrelia - cause of e.g. European and African relapsing fever

Borrelia burgdorferi, Lime disease spirochete - cause of Lyme disease; transmitted primarily by ticks of genus Ixodes

leptospira - important pathogens causing Weil's disease or canicola fever