Otostrongylus circumlitus (Railliet, 1899) was found in 5% (16/308) of grey seals (Halichoerus grypus), 6% (1/17; intensity = 38) of harbour seals (Phoca vitulina), and none of 100 harp seals (Phoca groenlandica) from eastern Canada and none of 31 ringed seals (Phoca hispida) from Holman, Northwest Territories. Eighty-two percent of these infections were observed in young-of-the-year seals. Filaroides (Parafilaroides) gymnurus (Railliet, 1899), detected in nodules in the superficial parenchyma of the lungs, infected 24% (5/16) of grey seals, 27% (4/15) of harbour seals, 57% (29/51) of harp seals, 81% (25/31) of ringed seals, and one stranded bearded seal (Erignathus barbatus) (new host report for harp, ringed, and bearded seals; new locality report for Holman). Filaroides (Parafilaroides) hispidus Kennedy, 1986 was found in systematically sliced lungs of grey seals (2/3; new host report) and ringed seals (2/7) but not in harp seals (n = 11) or harbour seals (n = 5). Intensity ranged from 37 to 3570 for F. (P.) gymnurus and from 295 to 1196 for F. (P.) hispidus. No detrimental effect on body condition of seals could be associated with infection by lungworms.
Metastrongyloid Nematode (Otostrongylus circumlitus) Infection in a Stranded California Sea Lion (Zalophus californianus)— a New Host-parasite Association