Ultrastructural changes observed in Fasciola hepatica following treatment with nitroxynil and triclabendazole, alone and in combination

Using scanning electron microscopy (SEM) and transmission electron nncroscopy (TEM), the effects of the fasciolicide nitroxynil, on the tegumental surface and ultrastructure ofFasciola hepatica have been assessed. The SEM findings revealed that nitroxynil severely disrupted the tegument of triclabendazole-susceptible isolates, both in vivo and in vitro. Nitroxynil also caused progressively severe disruption to the tegumental surface ofF. hepatica with tegumental sloughing observed at longer exposure periods in vivo. Surface changes observed after 24 h incubation in vitro were similar to those seen after longer time periods in vivo. The ultrastructural changes were examined by TEM, and again showed that nitroxynil causes severe and progressive disruption to the tegumental syncytium of the fluke, both in vivo and in vitro. The route of entry of nitroxynil and uptake via the tegument and gut of the liver fluke were explored both in vivo and in vitro. In vivo nitroxynil- was found to severely disrupt first the gut and secondly the tegument of F. hepatica and in vitro the tegument was more disrupted than the gut. Morphological and ultrastructural studies on the activity of TCBZ against the Fairhurst and Oberon isolates supported efficacy data (Dr J Boray) and confirmed the Fairhurst isolate can be regarded as TCBZ-susceptible, whilst the Oberon isolate is TCBZresistant. The combination of nitroxynil and triclabendazole was studied in vitro. SEM and TEM results revealed that the combination of nitroxynil and TCBZ was more disruptive than either of the individual drugs at half-strength and also more effective than both drugs at full-strength.EThOS - Electronic Theses Online ServiceGBUnited Kingdo