Trematodes

• Trematodes Commonly known as flukes
• Trematodes Belong to the class Trematoda or Digenea.
• Trematodes May be hermaphroditic or dioecious (reproduce via

  separate sexes)
• Most flukes are hermaphroditic except Schistosoma

  spp. (blood flukes)
• Morphologically, flukes are fleshy, leaf-shaped worms.
• Unlike tapeworms, flukes have a digestive tract.
• Unlike tapeworms, flukes have a digestive tract. two muscular suckers : an oral type, which is the beginning of an incomplete digestive system and a ventral sucker, which serves for attachment.
• fluke eggs vary in appearance and are primary morphologic stage that usually recovered from humans.
• some eggs may possess a lid-like structure that can flip open to release its contents. this lead-like structure is called operculum and is present in the eggs of Fasciolopsis and Fasciola.
• In Schistosoma spp., the eggs of the various members may be differentiated based on the presence and location of spines
• Unlike in cestodes infections, humans never serve as intermediate hosts for the flukes.
• In general, flukes have two intermediate hosts except for the blood flukes where there is only one intermediate host.
• Common to all trematodes, first intermediate hosts are mollusks (snails and clams) where asexual reproduction takes place.
• The second intermediate host varies depending on the parasite.
• Sexual reproduction of flukes occurs in humans.
• In most cases, humans acquire the infection through ingestion of undercooked or raw second intermediate host.
• Skin penetration by the infective larvae is the major mode of transmission for blood flukes.