In vitro exposure of F. gigantica to heavy metal At 100 mg/L, the relative motility was 0.75 which means 25% of the flukes were dead while at 150 mg/L, the relative motility value was 0.61 which means 39% of the flukes were dead. And finally at 200 mg/L, the relative motility value was 0.30 which means 70% of the flukes were dead