Intestinal Spirochetosis in Pigs

The etiologic agent of intestinal spirochetosis is Brachyspira pilosicoli. B pilosicoli is emerging as an important pathogen of humans, especially in indigenous populations and immunosuppressed patients. The organism is transmitted orally and survives extremely well in the environment. B pilosicoli has been isolated from a wide variety of animals, including waterbirds, rodents, and dogs. It has been shown to cause diarrheal disease in pigs, chickens, and humans by experimental inoculation and in natural occurrence; however, the pathogenesis is not well studied. As with swine dysentery, Bpilosicoli colonization and disease expression can be appreciably influenced by alteration of dietary fiber.

Clinical signs of intestinal spirochetosis typically occur in 8- to 12-week-old pigs and often occur 1–2 weeks after movement or commingling. Feces from affected pigs appear similar to wet cement, and this mild diarrhea commonly lasts for 3–6 weeks. Uncomplicated disease is not usually associated with appreciable mortality; however, pigs may have reduced appetite and grow slowly, causing economic losses.

The differential diagnosis of intestinal spirochetosis often includes intestinal salmonellosis Intestinal Salmonellosis in Pigs Enteropathogenic salmonellae cause inflammation and necrosis of the small and large intestines, resulting in diarrhea. Infection with certain serotypes may be accompanied by generalized sepsis... read more , proliferative enteropathy Porcine Proliferative Enteropathy Porcine proliferative enteropathy is a common diarrheal disease of growing-finishing pigs and young breeding pigs, characterized by hyperplasia and inflammation of the jejunum, ileum, cecum... read more , swine dysentery Swine Dysentery Swine dysentery is a mucohemorrhagic diarrheal disease of pigs that is limited to the large intestine. Swine dysentery is most often observed in growing-finishing pigs and is associated with... read more , and whipworm infection Trichuris sp in Pigs Photomicrograph of Trichuris suis egg. Note the characteristic lemon shape and polar plugs (opercula). Long dimension of egg, approx 50–68 mcm. Trichuris suis (whipworm) is found... read more . B pilosicoli and other Brachyspira spp can be isolated on selective agar under anaerobic conditions. Biochemical tests have historically been used for species identification; however, PCR assays, sequencing, and mass spectrometry are increasingly available and more consistent. PCR assays for Bpilosicoli that can be applied directly to fecal samples are also available. Histopathologic evaluation with silver stains is useful to identify end-on attached bacteria and to exclude other disease conditions.

Treatment and prevention of intestinal spirochetosis are similar to those of swine dysentery Swine Dysentery Swine dysentery is a mucohemorrhagic diarrheal disease of pigs that is limited to the large intestine. Swine dysentery is most often observed in growing-finishing pigs and is associated with... read more . Administration of drugs such as tiamulin, lincomycin, and carbadox has historically been effective; however, increasing antimicrobial resistance has been reported in several countries, and minimum inhibitory concentration testing is recommended before beginning treatment. It is unknown whether the agent can be eradicated without total depopulation, as for swine dysentery; however, given the number of potential reservoir hosts and environmental survival, it seems unlikely.