Folia Parasitologica

The occurrence of the avian schistosome Allobilharzia visceralis Koláøová, Rudolfová, Hampl et Skírnisson, 2006 (Schistosomatidae) in the tundra swan, Cygnus columbianus (Anatidae), from North America

Sara V. Brant

Folia Parasitologica 54 99-104 (2007)

Twelve tundra swans, Cygnus columbianus (Ord), from Nevada and one from New Mexico were collected and examined for schistosomes. Mature worms, determined as Allobilharzia visceralis, were found in 92% of the swans, in the inferior mesenteric vein of the large intestine and its branches. In 12 cases, there was endophlebitis of the inferior mesenteric vein. The morphology of the worms is consistent with the recently described genus Allobilharzia. Placement in this genus was confirmed also by phylogenetic analysis of nuclear 28S, 18S and, internal transcribed spacer (ITS) ribosomal DNA (rDNA), and mitochondrial cytochrome oxidase I (CO1) sequences. Data further suggest the worms are conspecific with the European A. visceralis, the only described species of the genus and which was found to be the sister taxon to the most diverse avian schistosome genus, Trichobilharzia. This is the first report of a schistosome infection from native swans in North America.

Address for correspondence: S. Brant, University of New Mexico, Department of Biology, 167 Castetter Hall, Albuquerque, New Mexico 87110, USA. Phone: ++1 505 277 2517; Fax: ++1 505 277 0304; E-mail: sbrant@unm.edu