Taenia solium

MICROBIOLOGY

• Taenia solium (pork tapeworm) and Taenia saginata (beef tapeworm) are intestinal cestodes.
  • Cysticercosis including neurocysticercosis is the main concern of these tapeworm infections, caused by Taenia solium.
• Life cycle: additional details in CDC illustration.
  
  • Eggs or gravid proglottids are passed in the stool.
  • Pigs ingest contaminated vegetation, and oncospheres hatch in the intestine.
  • Organisms invade the intestinal wall, migrate to striated muscles, and develop into cysticerci.
  • Humans ingest raw or undercooked infected meat, and gastric juices activate larvae, leading to evagination of scolex and attachment to the small intestine.
  • Over 2-4 months, cysticercus develops into an adult tapeworm; may grow up to 7 meters in length.
• Adults have up to 1,000 proglottids, each containing 50,000-100,000 eggs.
• Pigs are intermediate hosts; humans acquire intestinal tapeworm by eating undercooked pork containing cysticerci.
• Humans acquire disseminated cysticercosis by ingesting eggs in food/water contaminated by human tapeworm carriers.