Life Cycle Patterns

• What is the first step in the life cycle of trematodes?

  Adult worms lay eggs in vertebrate hosts
• What happens to the eggs laid by adult trematodes?

  They hatch into miracidium inside snail IHs
• What is the role of the miracidium in the trematode life cycle?

  It develops inside snail intermediate hosts
• What does the miracidium develop into while inside the snail?

  Sporocyst and then redia
• What does the redia contain in the trematode life cycle?

  Germinal balls that grow into cercaria
• What is the third type of larva produced by the redia?

  Cercaria
• What happens to cercariae after they emerge from the snail?

  They become free-swimming
• How can free-swimming cercariae enter a host?

  By penetrating skin or attaching to vegetation
• What occurs when cercariae enter a secondary host?

  They attach to subcutaneous tissues and encyst
• What do cercariae become after encysting in the secondary host?

  Metacercariae
• What is the infective stage for the definitive host in trematodes?

  Metacercariae
• MNEMONIC for Life Cycle

  • MS. aRCi Muñoz
  • Miracidium – ciliated larva
  • Sporocyst
  • Redia
  • Cercaria
  • Metacercaria