Cestodes: Hymenolepis nana (Dwarf tapeworm Life cycle)
Hymenolepis nana: Dwarf worm
- Small worm with a short life span.
- Infection is common, especially among children.
Life Cycle:
- The life cycle of this cestode does not always involve an intermediate host:
- Adults develop in humans, and eggs are passed in feces.
- Autoinfection is also possible, particularly in children, and can lead to significant, long-term infection.
- Infects rodents via arthropod intermediate hosts.
- Humans ingest eggs in contaminated water/food.
- Eggs release onchospheres (hexacanth larvae).
- Oncospheres invade the intestinal villi and become cistercoid larvae.
- The villi rupture and cysticercoids are released into intestinal lumen.
- Cysticercoids evaginate their scoleces and attach to intestinal mucosa; then develop into adult forms.
- Adults produce gravid proglottids, and eggs are passed in feces.