Epidemiological characteristics of an invading parasite: Dicrocoelium dendriticum in sympatric wapiti and beef cattle in southern Alberta, Canada.

Previous surveys of wild ungulates indicate that the liver fluke, Dicrocoelium dendriticum, was rare in the Cypress Hills area of southeastern Alberta. However, 41 of 59 wapiti (Cervus elaphus) sampled during the 2003 and 2004 hunting seasons from this region were infected, with 7 hosts containing >1,000 worms. Prevalence and mean intensity were similarly high in sympatric beef cattle and mule deer. Worm abundance in wapiti was age related, with calves containing significantly higher numbers of worms (mean +/- SD abundance = 825 +/- 1098) than adults (107 +/- 259). This pattern with host age was not evident in beef cattle, although the smaller sample sizes may be a contributing factor. These results indicate that D. dendriticum is now well established in Cypress Hills Park, circulating between at least 3 species of sympatric ungulates, including beef cattle.