Brachyspira pilosicoli has been reported in which hosts?

• A. Pigs, birds, and humans
• B. Pigs only
• C. Birds only
• D. Humans only

Answer: (A)

Brachyspira pilosicoli has a broad host range that includes both animals and humans, reflecting its zoonotic potential. In pigs, it’s recognized as porcine intestinal spirochetosis, where the organism colonizes the large intestine and can contribute to mild diarrhea or remain subclinical. In birds, it causes avian intestinal spirochetosis, affecting the intestinal tract and ceca of poultry and other birds. In humans, intestinal spirochetosis is described as a colonization of the large intestine that can be associated with chronic diarrhea and abdominal symptoms, though it may also be asymptomatic. The ability to infect multiple hosts explains why it’s considered across veterinary and medical contexts, rather than being limited to a single species. Detection typically relies on histology showing spirochetes attached to the apical surfaces of colonocytes, with molecular methods providing confirmation.