Effects of copper sulphate on in vitro encystment of the cercariae of Echinostoma caproni.

The effects of various concentrations of copper sulphate were studied on in vitro encystment of Echinostoma caproni in a Locke's-artificial spring water (ASW) (1:1) medium. Cercariae were killed in 10,000 mg l(-1) CuSO4 in Locke's-ASW (1:1) within 24 h and extruded cystogenous material to produce an abnormal cyst wall. The 'emergency response' of encystment to high concentrations of copper reported for Parorchis acanthus cercariae did not occur in E. caproni. Concentrations of 1000 mg l(-1) and 100 mg l(-1) CuSO4 in Locke's-ASW (1:1) also killed the cercariae without encystment by 48 h. A concentration of 10 mg l(-1) CuSO4 in Locke's-ASW (1:1) allowed for normal in vitro encystment within 48 h and these cysts were capable of excystation in a trypsin-bile salts medium.