Brachyspira spp. are anaerobic, flagellated and helically shaped (spirochaete) bacteria which are found worldwide.
Hosts: Brachyspira spp. can colonize caeca and less frequently the colon of chickens, pheasants, turkeys, partridges, ducks, geese and rheas.
The most common species of Brachyspira involved in enteric infection of these birds are B. pilosicoli and B. intermedia; less commonly B. alvinpulli and B. hyodysenteriae are involved in these enteric infections.