Published Web Locationhttps://doi.org/10.1002/9781118960608.fbm00308
Cells are helical with regular or irregular coils. 0.2-0.3 µm in diameter and 10-40 µm in length. Cells do not have hooked ends. Motile. Inner and outer membrane with periplasmic flagella with 7 to 20 subterminal insertion points. Aniline-stain-positive. Microaerophilic. Most members of the family cultivable in complex media that includes N-acetylglucosamine. Optimum growth between 33 and 38° C. Diamino acid of peptidoglycan is ornithine. Lacks a lipopolysaccharide. Linear chromosome and plasmids with hairpin telomeres. The family currently accommodates the genera Borrelia and Borreliella. Members of the family are host-associated organisms that are transmitted between vertebrate reservoirs by a hematophagous arthropod, in all but one case, a tick. Members include the agents of relapsing fever, Lyme disease, and avian spirochetosis.