Experimental infections of muskoxen (Ovibos moschatus) and domestic sheep with Umingmakstrongylus pallikuukensis (Nematoda : Protostrongylidae): parasite development, population structure, and pathology

Three captive muskoxen (Ovibos moschatus) were successfully infected with t hird-stage larvae of Umingmakstrongylus pallikuukensis digested or emerged from the slugs Deroceras reticulatum and D. laeve, for the first time compl eting the life cycle of this parasite under experimental conditions. The co urse of parasite development and patency was followed for 26 months post in fection (p.i.) using fecal examinations and radiography. The prepatent peri ods in two of the muskoxen were 91 and 95 days and the patent period in one extended for 23 months. Larval production peaked 13-14 months p.i. On post mortem of two of the muskoxen at months 14 and 26 p.i., adult parasites wer e found only within pulmonary cysts and cysts were randomly distributed bet ween left and right lungs. Cyst dimensions were positively correlated with the number of adult parasites they contained. On postmortem of the third mu skox at day 97 p.i., not all adult parasites were within typical cysts; two were found free in interlobular septa. First-stage larvae were recovered f rom lung cysts of this animal but not from feces. Lung pathology in all thr ee muskoxen appeared localized and associated with the adult nematodes. Inf ection of two sheep with third-stage larvae of U. pallikuukensis did not re sult in parasite establishment.