First identification of "Brachyspira hampsonii" in wild European waterfowl.

Anseriformes deserve special attention in the epidemiology of Brachyspira spp. because diverse Anseriformes species have been described to act as highly efficient carriers of several Brachyspira spp. that can also infect livestock. The aim of this study was to investigate the prevalence and diversity of Brachyspira spp. in waterfowl that winter in Spain. Brachyspira spp. were isolated from 51 of the 205 faecal samples collected from graylag geese and mallards in the Villafáfila Lagoons Nature Reserve (Northwestern Spain). The Brachyspira species identified through phenotyping, PCR and sequencing of the nox gene were B. pilosicoli (5.9%), B. alvinipulli (11.8%), "B. hampsonii" (19.6%), B. murdochii (23.5%) and B. innocens (39.2%). The most relevant finding of this study is the description of "B. hampsonii" in specimens from birds for the first time. Phylogenetic analysis of the nox gene sequences grouped all of the obtained "B. hampsonii" isolates into a cluster with Brachyspira strains previously identified by others as "B. hampsonii" and separated from other Brachyspira spp. isolates and reference strains. Additionally, this cluster was related to clades that grouped B. murdochii and B. innocens isolates. The identification of "B. hampsonii" was also achieved in 8 of the 10 isolates by sequencing the16S rRNA gene and tlyA gene. Regardless of the species identified, no antimicrobial resistance was observed in any of the enteropathogenic isolates recovered. This is the first description of "B. hampsonii" in European waterfowl, which might represent hosts that serve as natural reservoirs of this Brachyspira species. This finding indicates that this spirochete is not limited to North America, and its presence in wild birds in Europe poses a risk of transmission to livestock.