Development of a novel video system for monitoring anthelmintic resistance

The aim of this thesis was to develop novel low cost, rapid systems for the detection of anthelmintic resistance by using video analysis to detect the drug induced neuromuscular behaviour of parasites. Tests for resistance to the anthelmintics levamisole and ivermectin were developed with the sheep nematodes Teladorsagia circumcincta and Haemonchus contortus. A test for triclabendazole resistance was also developed using the liver fluke Fasciola hepatica. Video analysis tests for the L1 and L3 larval stages of T. circumcincta and H. contortus were developed. For each drug, test concentrations and incubation times were established and known susceptible and resistant strains were recorded and analysed using the video tracking computer software ‘Inchworm’. A levamisole assay was established that showed significant differences in net speed, distance moved and time spent moving of levamisole susceptible and resistant strains of T. circumcincta and H. contortus after incubation in drug treatment for 30 minutes. H. contortus larvae required 10-fold lower concentrations of levamisole than T. circumcincta to detect the significant differences between the strains. Once the eggs had hatched, a drug resistant test could be performed on larvae of both species in 30 minutes with minimum analysis. Results from the ivermectin assay varied between species. Ivermectin resistance was clearly indicated with a dose response assay on L1 H. contortus larvae. Dose response assays were inconclusive for T. circumcincta. The video assays showed significant differences between ivermectin susceptible and resistant L1 H. contortus strains after 2.5 hours incubation in drug concentrations of between 100ng/ml and 300ng/ml ivermectin. Significant differences were also found when L1 T. circumcincta larvae were incubated for 2.5 hours in 25ng/ml ivermectin.