Phenotypic and genetic diversity among intestinal spirochaetes (genus Brachyspira) in free-living wild mallards (Anas platyrhynchos) sampled in southern Sweden.

Brachyspira spp. are anaerobic intestinal spirochaetes that colonize vertebrates. Some species cause enteric diseases in pigs, chickens and possibly in humans, whereas others display a commensual relationship with their hosts.