Taenia solium (Pork tapeworm)
- Pigs (or cows) ingest vegetation contaminated with the parasites' eggs; humans then ingest the infected meat.
- If the worm burden is high, infection can cause gastrointestinal problems.
Cysticercosis occurs when humans ingest Taenia solium*
eggs in food or water contaminated by
human feces.
– Once ingested, the eggs give rise to larvae that form
cysts in the tissues.
– This is particularly serious when cysts form in the
brain or spinal cord:
Neurocysticercosis occurs when
Taenia solium larvae form
cysts and calcified lesions in the CNS.
– This is the leading cause of
epilepsy in endemic nations.
- Other neurological manifestations can occur depending on the location and size of the lesions, including obstructive hydrocephalus.
Taeniasis
1. Pigs are infected when they eat contaminated vegetation.
2. In the pig, oncospheres hatch and penetrate the intestinal wall.
– Move to striated muscle.
3. Oncospheres develop to cysticerci larvae in muscle tissue. These can survive for several years.
4. Humans eat the pork with cysticerci.
5. Cysticerci become adult tapeworms.
6. Adult tapeworms use scolex to attach to small intestine wall, and can live here for years.
7. Adults produce proglottids that mature, become gravid.
8. Gravid proglottids detach and migrate to anus.
9. Proglottids are released in stool, and then eggs are released to environment. A single proglottid can produce up to 50k eggs.
- Infection is usually asymptomatic.
Escobar's Pathologic Stages
- Vesicular with living larva
- Viable parasite w/intact membrane.
- Colloidal with larva degeneration
- Parasite dies and cyst fluid becomes turbid.
- Edema surrounds the cyst.
- Most symptomatic stage.
- Granular nodular with cyst thickening
- Edema decreases.
- Cyst retracts.
- Nodular/Calcification
- End-stage/quiescent: calcified cyst.
- No edema.
