Retrospective surveillance of necrotising typhlitis associated with Brachyspira spp. in British rhea. Brachyspira spp. in Rheas

This paper describes a retrospective analysis of necrotising typhlitis in common rhea (Rhea americana) diagnosed in the United Kingdom by the Animal & Plant Health Agency (APHA). From January 2008 to January 2020, eight cases of spirochetal typhlitis associated with Brachyspira spp. were identified. Gross examination was combined with selective anaerobic culture, PCR and histopathology to diagnose typhlitis associated with spirochetal infection. Whole genome sequencing was subsequently utilised on isolates from six of the eight submissions, overcoming issues with traditional testing methods and yielded gains in identification of Brachyspira to species level. Brachyspira hyodysenteriae, an organism traditionally associated with typhlitis in rheas, was isolated in three sequenced submissions. One of these also demonstrated coinfection with Brachyspira intermedia. Brachyspira suanatina, Brachyspira hampsonii and Brachyspira alvinipulli were identified by sequencing as single infections in the remaining three animals. This report demonstrates the ability of Brachyspira species other than B. hyodysenteriae to colonise the caeca of rhea with pathogenic effects. The advantages of identification of Brachyspira to species level using whole genome sequencing are demonstrated.