Control of Fascioloides magna in white-tailed deer (Odocoileus virginianus).

摘要

In Texas, USA, the definitive host for Fascioloides magna is the white-tailed deer (Odocoileus virginianus), while cattle (Bos taurus) and feral hogs (Sus scrofa) are the dead-end hosts. Suitable habitat exists to support the parasite and its snail intermediate host, Lymnae bulimoides (Foreyt, 1975). In theory, the parasite could be controlled by treating free ranging deer to reduce pasture contamination by parasite eggs.;The efficacy of triclabendazole at a dose of 10 mg/kg body weight was 100% for treatment of naturally acquired Fascioloides magna infections in white-tailed deer. No adverse reactions of the drug were observed.;A field trial using triclabendazole medicated corn bait (concentration of 11 mg/kg) was conducted on three areas at the Welder Wildlife Refuge, Sinton, Texas, USA. The areas were designated as treated, baited control and unbaited control. Transmission of the parasite was confirmed before the beginning of the study. Deer were baited during the winter of 1987, 1988, and 1989. Prevalence of the parasite in deer was significantly lower in the treatment pasture than in the baited or unbaited control areas. This indicates that free ranging deer can be treated for F. magna by the use of medicated bait. The effects of the treatment on the transmission of the parasite was monitored by grazing sentinel calves on the baited pastures. However, because of a drought that began in 1987, transmission was not observed throughout the study when the effects of the treatment should have been evident.;To improve diagnosis secretory/excretory antigens of F. magna and Fasciola hepatica were compared by Western blot analysis using sera from experimentally infected deer and cattle. Prominent polypeptides were identified for both parasites. A 27 kD polypeptide of F. magna cross-reacted with sera from F. hepatica infected cattle, while reactions of the 22 and 17 kD polypeptides were specific. A 46 and a 26 kD polypeptide of F. hepatica, cross-reacted with sera from F. magna infected animals. A 15 kD polypeptide reacted specific for F. hepatica. These polypeptides that react specifically for each parasite can be used for species specific diagnosis.