Brachyspiral colitis: An evolving problem

D.J. Hampson

The name “Brachyspiral colitis” recently was introduced into the literature on swine diseases to describe the situation where colitis, diarrhea and/or dysentery occur in pigs infected with one or more pathogenic Brachyspira species (Hampson, 2012). The term was created to emphasise an increasing understanding of the diversity of anaerobic intestinal spirochetes in the genus Brachyspira and the fact that a number of different species may have a role in inducing inflammation in the large intestine. Until only a few years ago most veterinarians would have felt comfortable with the concept of there being two pathogenic Brachyspira species capable of causing disease in pigs, each associated with a distinct named disease. The first was the strongly hemolytic Brachyspira hyodysenteriae causing swine dysentery, a severe mucohemorrhagic colitis seen mainly in grower and finisher pigs. The second was the weakly hemolytic Brachyspira pilosicoli causing porcine intestinal spirochetosis (porcine colonic spirochetosis), a milder form of colitis seen mainly in weaner and grower pigs. Other weakly hemolytic species colonising pigs generally were thought of as being commensals. Now it is known that there are at least three strongly hemolytic pathogenic Brachyspira species that may infect swine and cause a swine dysentery-like disease; furthermore, there is increasing evidence that one or more of the other weakly hemolytic species besides B. pilosicoli also have pathogenic potential in swine and other species. Specifically, the weakly hemolytic Brachyspira murdochii is increasingly being implicated as an occasional cause of mild colitis in pigs (Jensen et al., 2000; Weissenböck et al., 2005; Komarek et al., 2009; Osorio et al., 2013). It is also clear that individual pigs on different farms may be colonised with more than one Brachyspira species and/or strains that may contribute towards causing disease symptoms. In and interesting parallel, the ceca and colon of adult chickens and other poultry species may be colonised by a number of Brachyspira species that can induce inflammation, wet feces and reduced egg production. This disease complex (most commonly is associated with B. intermedia and/or B. pilosicoli) currently is known as “Avian Intestinal “Spirochetosis” (Hampson, 2013), but for clarity and consistency with the revised disease nomenclature in pigs it might be better if it was to be called “Brachyspiral typhlitis”.

Brachyspiral colitis: An evolving problem

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