Taenia solium: Pork tapeworm &
Taenia saginata: Beef tapeworm
- Both can cause taeniasis.
- 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.
Adult worm is 3-5 meters (Taenia solium*)
Cysticercosis is a more serious infection that 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 a significant cause of
epilepsy worldwide; other neurological manifestations depend on the location and size of the lesions.
Taeniasis
1. Pigs are infected when they eat contaminated vegetation.
2. In 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.
Cysticercosis
1. Humans ingest eggs.
2. The eggs hatch and oncospheres penetrate the intestine and move to striated muscles and other tissues (including CNS, eye, liver, etc)
3. The oncospheres become cysticerci in these tissues.
- In theCNS, cysts can cause serious problems.
Image Credits:
https://www.cdc.gov/dpdx/taeniasis/index.html
