Cases of spirochete-associated necrotizing typhlitis in captive common rheas (Rhea americana).

Ceca from greater or common rheas (Rhea americana) with gastrointestinal disease were collected from diagnostic labs and avian pathologists across the United States. The ceca were evaluated for the presence of spirochetes and necrosis using hematoxylin and eosin stain or Warthin-Starry silver-stained tissue sections and anaerobic culture. Spirochete-associated necrotizing typhlitis was documented in 11 states. Most cases were reported in the summer and fall and occurred in rheas less than 5 mo of age. Spirochetes isolated from ceca with necrosis were either strongly or weakly beta-hemolytic. All spirochetes isolated from ceca without necrosis were weakly beta-hemolytic. Rheas might be host to both pathogenic and nonpathogenic spirochetes.