Naturally occurring spirochetes in the colonic mucosa of raccoons (Procyonlotor)

The large intestines of 21 raccoons (Procyon lotor; 11 wild caught, 10 labo ratory confined) were examined for the presence of intestinal spirochetes. Light microscopy of sections stained with hematoxylin and eosin and Warthin -Starry stain showed the presence of spiral shaped organisms deep within th e lumina of intestinal glands at the ileocolonic junction of 16 raccoons (7 6% prevalence). All laboratory-confined, group-housed raccoons harbored the organisms, but only 6/11 (55% prevalence) live-trapped raccoons were posit ive for these spirochetes. The organisms were free in the glandular lumina, and there were no microscopic lesions. Two types of spirochetes were ident ified in the colonic glands: a slender spirochete 10-13 mum in length, 0.3 pm in diameter, and possessing long, thin tapered ends and a larger, regula rly waved spiral organism (0.5 mum in diameter). The slender spirochete did not resemble any of the known spirochete genera and failed to grow on medi um used to propagate oral treponemes and members of the genus Brachyspira.