Unravelling Spirocerca vulpis from red foxes from Switzerland: a 20-year-old record.

Spirocerca vulpis is a parasitic nematode of red foxes associated with gastric nodule formation. Since its description in 2018, this species has been reported in red foxes from Spain, Bosnia and Herzegovina, Italy, and Portugal. We present here the analysis of uncharacterized nematodes obtained from gastric nodules of a red fox from Switzerland in 1999. The specimens were identified as S. vulpis based on the observation of teeth-like structures in the buccal capsule and a 99.4% sequence identity to S. vulpis DNA from Spain. Phylogenetic analysis demonstrated the clustering of the Swiss sequences in a different group from specimens of other geographical locations. Altogether, this study constitutes the first report of S. vulpis in Switzerland and a report of the oldest specimen of this species in the world. Our findings highlight the widespread distribution of S. vulpis in Europe which may be facilitated by the free-roaming nature of red foxes.