Trematode diseases

Eggs of the trematode worm which eliminated into water via human or animal faeces are ingested by certain snails. The eggs hatch within the snail and develop into large numbers of free-swimming larval organisms that escape into the water and penetrate under the scales or in the flesh of freshwater fish. Humans become infected when eating the fish either raw or undercooked. The ingested organisms migrate to the human bile ducts where they mature and remain during their life span, shedding eggs into the bile.