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This article describes for the first time the presence of Brachyspira hampsonii in migrating waterfowl, which might be the natural reservoir hosts of this Brachyspira species. Different species of waterfowl should accordingly be considered a potential source of B. hampsonii for swine.
During the study, fresh stool samples of different species of birds were collected randomly from soil in different parts of the banks of the lagoons during the winter 2010‐2011 in the Natural Reserve of the Lagoons of Villafáfila (Spain). Samples were cooled and transported immediately to the laboratory and cultured anaerobically on TSA
plates supplemented with 5% ovine blood and antibiotics (CVS) for Brachyspira spp isolation following
the usual procedures.
The most relevant finding is the description for the first time of B. hampsonii from bird samples. The frequency of detection of this specie differed slightly depending on the origin of the samples. Thus, 7 of 147 goose samples were positive (4.9%) while 3 of 34 (9.0%) of mallard samples contained B. hampsonii. However, the proportion of B.hampsonii isolates among all spirochaetes isolated was very similar for both species (20.6% for goose and 17.6% for mallards). On the contrary, the species B. hyodysenteriae and B. suanatina were not identified in this study, although positive amplicons of tlyA gene of B. hyodysenteriae were detected in 14 isolates which were classified as B. hampsonii (50%), B. innocens (7.1%), B. murdochii (28.6%) and B. alvinipulli (14.3%). When the partial tlyA gene of B. hampsonii isolates was sequenced, similarity to B. hyodysenteriae was never 100%, in contrast to what happens between different B. hyodysenteriae strains. Moreover, homology to B. intermedia and B. hyodysenteriae was similar.
These results indicate that cross‐reactions can occur between B. hyodysenteriae and B. hampsonii in the
PCR reactions used routinely for diagnosis. This fact can have consequences for the appropriate
diagnosis of brachyspiral colitis and for the evaluation of the real incidence of B. hampsonii in the field,
especially taking into consideration that B. hampsonii can exhibit strong β‐haemolysis in culture. In fact,
all 10 strongly beta‐haemolytic spirochaetes isolated in this study were identified as B. hampsonii.
Phylogenetic analysis of nox gene sequences grouped all B. hampsonii Spanish isolates into a cluster that
was independent of other Brachyspira spp Spanish isolates and reference strains. This cluster is related
to clades that group B. murdochii and B. innocens. Besides, these isolates are grouped together with
Brachyspira strains previously identified in USA and Canada as B. hampsonii, what supports the
identification of isolates obtained in Spain as B. hampsonii. In addition, phylogenetic analysis of nucleotide sequences indicates that B. hampsonii obtained in this study form two monophyletic clades. Thus, the majority of isolates were grouped together with Brachyspira KC35 and Brachyspira EB106 (previously identified as B. hampsonii), while only 2 out of 10 isolates gathered together with Serpulina sp P280/1.
The study concludes that prevalence of B. hampsonii in waterfowl appears to be relatively high (10 isolates of 173 random samples). This could indicate that waterfowl are the natural reservoir hosts of this spirochaete.
Considering that the wintering population of waterfowl in Spain spreads to several other countries of
Europe, it seems probably the presence of this species of Brachyspira in other northern European
countries. It seems necessary to test also the presence of B. hampsonii in the waterfowl populations of
North America.
Pedro Rubio. Isolation of Brachyspira hampsonii from migrating waterfowl in Spain. DIGESPOR (Group of Research on Digestive Infections of Pigs). Faculty of Veterinary. University of León, Spain.
