Detection of Brachyspira hampsonii genomovar I in Ontario

Đurđa Slavić, Murray Hazlett

Animal Health Laboratory, University of Guelph, Guelph, ON

AHL Newsletter 2020;24(4):11.

In September of this year, Brachyspira hampsonii genomovar I (previously clade I) was detected by qPCR in porcine fecal samples submitted from a sow herd.  The results were confirmed by sequencing of the PCR product.  Since 2013, all porcine samples submitted to the AHL for qPCR for Brachyspira profile testing have been tested for the presence of B. hyodysenteriae, B. pilosicoli, B. hampsonii genomovar I and B. hampsonii genomovar II, as well as for the presence of Brachyspira spp.  Whereas in the past B. hampsonii genomovar II was detected in samples submitted from out of the province, this is the first time that B. hampsonii genomovar I was detected in samples submitted from Ontario.  An AHL database search revealed that since January 2018, 120 submissions totaling 276 samples were tested by Brachyspira profile qPCR.  Eleven cases were positive for B. hyodysenteriae and 9 cases were positive for B. pilosicoli.  Not surprisingly, both pathogens were detected in 3 of these cases, confirming the notion that more than one species of Brachyspira can be present in the same animal.

There are different species of Brachyspira associated with clinical diseases in grower-finisher pigs including B. hyodysenteriae, B. hampsonii, B. pilosicoli, B. suantina and B. murdochii.  Whereas strongly haemolytic Brachyspiras (i.e., B. hyodysenteriae, B. suantina (currently in Europe only), and B. hampsonii) are associated with severe mucohemorrhagic diarrhea (Figs. 1A and 1B), the weakly hemolytic ones usually cause colonic spirochetosis characterized by diarrhea and/or colitis (Fig. 1C). 

Brachyspira hampsonii is a new species of strongly haemolytic Brachyspira spp. that has been divided into three different genomovars; namely, genomovar I, II, and III.  Genomovars I and II have been associated with severe mucohaemorrhagic diarrhea in North American pigs whereas genomovar III has been detected in pigs and migratory waterbirds in Europe.  No differences in clinical signs, gross or microscopic pathology have been observed between genomovar I and II in North American pigs or between disease caused by B. hampsonii and B. hyodysenteriae. 

AHL will continue to investigate any swine dysentery suspect cases in the future to monitor for the presence of different Brachyspira spp. in the Ontario swine population.  Veterinarians suspecting swine dysentery should submit feces or tissue samples to AHL for Brachyspira profile qPCR testing.  Culture is also available; however, the laboratory has to be notified in advance since a selective media for culture is made on an as-needed basis.   AHL

Figure 1.  A. Mucohemorrhagic enteritis due to Brachyspira hyodysenteriae (swine dysentery) courtesy of A.A. van Dreumel.  B. Swine dysentery showing necrosis and ulceration of superficial mucosa (arrows) (H&E).  C. Brachyspira pilosicoli with typical adherence of organisms to the colonic enterocyte surface producing a “brush-cut” appearance (arrow) (H&E).

Reference 

1. Mirajkar NS et al. Characterization and recognition of Brachyspira hampsonii sp. nov., a novel intestinal spirochete that is pathogenic to pigs. J Clin Microbiol 2016;54:2942-2949.