| Popis: |
Levamisole is one of the first anthelmintic in Bulgaria and is still widely used. Its frequent and not always proper application is a primary cuse for reduction of its efficacy to critical levels. To establish the presence of levamisole resistance among gastrointestinal strongylids (GIS), we used the following in vitro tests: Larval development assay (LDA), Egg hatch paralysis assay (EHPA), and Larval migration inhibition test (LMIT). The effective doses required to inhibit 50% of the larvae (ED50) were: for LDA from 0.198 to 1.785 μM; for EHPA from 0.095 to 13.274 μM; for LMIT from 0.140 to 2.812 μM. Based on world references we assumed that ED50 values of levamisole showing presence of resistance are over 1.56 μM for LDA, 2.45 μM for EHPA and 1.2 μM for LMIT. On the basis of results, in one of the 12 examined sheep herds, levamisole resistance was detected with ED50 values: in LDA – 1.786 μM; in EHPA − 13.274 μM and in LMIT − 2.812 μM. |
