General Rules for Trematodes

• What is the reproductive characteristic of all trematodes except schistosomes?

  They are hermaphroditic
• What type of eggs do trematodes have?

  Operculated eggs
• What is the general shape of trematodes?

  Leaf-like or tongue-shaped
• How many intermediate hosts do monoecious trematodes require?

  Two intermediate hosts
• What are the roles of the primary and secondary intermediate hosts for monoecious trematodes?

  • Primary IH: harbors early larval stage (e.g., mollusks, especially snails)
  • Secondary IH: harbors stage infective to humans (e.g., fish, crabs, another snail)
• Who is the definitive host for trematodes?

  Vertebrates or humans
• What is the infective stage for monoecious trematodes?

  Metacercaria
• What is the infective stage for dioecious trematodes?

  Fork-tailed cercaria
• What is the mode of transmission (MOT) for trematodes?

  Through food contaminated with infective forms