|
|||||
|
|
Susceptibility to IVM in a field strain of Haemonchus contortus subjected to four treatments in a closed sheep-goat flock in Kenya |
|
| Authors: | Gatongi P M Njoroge J M Scott M E Ranjan S Gathuma J M Munyua W K Cheruiyot H Prichard R K |
| Institution: | a Kenya Agricultural Research Institute, P.O. Box 57811, Nairobi, Kenya b Institute of Parasitology, Macdonald Campus of McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Que., Canada H9X 3V9 c Laboratory of Chemical Biology, National Institutes of Diabetes and Digestive and Kidney Diseases, NIH, Building 10, Rm 9B17, Bethesda, MD 20892, USA d Fort Dodge Animal Health, P.O. Box 5366, Princeton, NJ 08543, USA e Faculty of Veterinary Medicine, Kabete Campus, University of Nairobi, P.O. Box 29053, Kabete, Kenya |
| Abstract: | Susceptibility to IVM (IVM) of “strain A” Haemonchus contortus which had been exposed to IVM four times over a 2-year period was compared to IVM susceptibility of “strain C” H. contortus which had no prior field exposure to IVM, by in vivo and in vitro methods. In vivo, the percentage reduction in faecal egg counts (FEC) and the total worm counts (TWC) were compared between control animals (lambs and kids) and animals treated with low dose IVM (20 μg/kg). In vitro susceptibility to IVM was evaluated by larval migration inhibition (LMI) after the two strains of H. contortus were exposed to different concentrations of IVM. The dose response, measured as the proportion of larvae inhibited from migrating, was used to estimate LD50. Although differences in response to IVM in the in vivo determinations were not significant, “strain A” H. contortus had a significantly higher LD50 than “strain C” in the LMI assay. Coincident with the conduct of the in vivo experiment, it was observed that “strain A” H. contortus established and survived better than “strain C” in the control lambs. |
| Keywords: | Haemonchus contortus IVM Susceptibility Resistance Sheep Goats Larval migration inhibition Faecal egg count reduction Total worm count |
| 本文献已被 ScienceDirect PubMed 等数据库收录！ | |