What characteristic limits the survival of spirochetes outside of their hosts?

The characteristic that limits the survival of spirochetes outside of their hosts is their sensitivity to drying. Spirochetes are thin, spiral-shaped bacteria that are typically found in moist environments, such as within the bodies of their hosts. When exposed to dry conditions, spirochetes quickly lose viability because they lack robust mechanisms to resist desiccation. The outer membrane and cell structure of spirochetes do not provide sufficient protection against the harmful effects of drying, which leads to their rapid death outside of a host environment.

This sensitivity makes it challenging for spirochetes to survive in the external environment, limiting their transmission and infection routes primarily to direct contact with hosts or other moist environments. Understanding this characteristic is essential for studying the ecology and epidemiology of spirochetal infections, such as those caused by Borrelia or Treponema species.