Volume 14, Number 1—January 2008
THEME ISSUE International Polar Year
Integrated Approaches and Empirical Models for Investigation of Parasitic Diseases in Northern Wildlife
Eric P. Hoberg* , Lydden Polley†, Emily J. Jenkins†‡, Susan J. Kutz§, Alasdair M. Veitch¶, and Brett T. Elkin#
Author affiliations: *US Department of Agriculture Agricultural Research Service, Beltsville, Maryland, USA; †University of Saskatchewan Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada; ‡Environment Canada, Saskatoon, Saskatchewan, Canada; §University of Calgary Faculty of Veterinary Medicine, Calgary, Alberta, Canada; ¶Government of the Northwest Territories, Norman Wells, Northwest Territories, Canada; #Government of the Northwest Territories, Yellowknife, Northwest Territories, Canada
Figure 1. Life cycle of protostrongylid parasite: Umingmakstrongylus pallikuukensis in muskoxen definitive and gastropod intermediate hosts (12). Adult nematodes (for U. pallikuukensis, located in the lungs) lay eggs, which hatch to first-stage larvae (L1). L1 move up the airways, are swallowed, and pass in the feces, where they must invade the foot of gastropod intermediate hosts for further development to the infective third-stage larvae (L3). Development to L3 requires a minimum amount of heating and does not occur below a critical threshold; these development parameters vary among different protostrongylid species (6,7,13). Definitive hosts become infected by ingesting a gastropod containing L3 or, for some protostrongylids such as U. pallikuukensis, by ingesting L3 that have emerged from the gastropods and are free in the environment.
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