the sensitivity was determined using parasite-purified DNA. Background DNA samples comprising 10 of the total extracted from an infection-free Lymnaea sp. snail were spiked with 2.5 ng, I ng, 500 pg, 250 pg, 100 pg or 1 pg of F. hepatica DNA and run through PCR. Sensitivity was also tested with 2.5 ng, 500 and 100 pg in the presence of 20 of the DNA snail sample