Borrelia /bərel″ē·ə/ [Amédée Borrel, French bacteriologist, 1867–1936] , a genus of coarse, unevenly coiled helical spirochetes, several species of which cause tick-borne and louseborne relapsing fever. The organism is spread to offspring from generation to generation. This does not occur in lice. Many animals serve as reservoirs and hosts for Borrelia. The spirochete may be identified by microscopic examination of a smear of blood stained with Wright’s stain; it is also easily inoculated onto culture media for bacterial culture and identification.