Genetically distinct isolates of Spirocerca sp. from a naturally infected red fox (Vulpes vulpes) from Denmark

Spirocerca lupi causes formation of nodules that may transform into sarcoma in the walls ofaorta, esophagus and stomach of infected canids. In February 2013, post mortem examina-tion of a red fox (Vulpes vulpes) hunted in Denmark revealed the presence of several nodulescontaining adult worms of Spirocerca sp. in the stomach and the omentum.

The noduleslargely consisted of fibrous tissue with infiltration of mononuclear cells, neutrophilic gra-nulocytes and macrophages with hemosiderin deposition. Parasitological examination bythree copromicroscopic methods, sedimentation, flotation with saturated sugar-salt solu-tion, and sieving failed to detect eggs of Spirocerca sp. in feces collected from the colon.This is the first report of spirocercosis in Denmark, and may have been caused by a recentintroduction by migrating paratenic or definitive host.

Analysis of two overlapping par-tial sequences of the cox1 gene, from individual worms, revealed distinct genetic variation(7–9%) between the Danish worms and isolates of S. lupi from Europe, Asia and Africa.This was confirmed by phylogenetic analysis that clearly separated the Danish worms fromother isolates of S. lupi.

The distinct genetic differences of the current worms compared toother isolates of S. lupi may suggest the presence of a cryptic species within Spirocerca.