L24 (Worm Parasites) - B Flashcards
Four features of Cestodes (Tapeworms)???
- Monoecious (unisex)
- No digestive system
- Transmission by ingestion of ova
- Cause little or no harm – unless present in large numbers
What are three examples of tapeworms?
T. saginata
T. solium
D. latum
Which organism has the following features?
- Diecious
- Complete digestive system
- Wide variation in mode of transmission
A. Nematodes (Roundworms)
B. Cestodes (Tapeworms)
A. Nematodes (Roundworms)
Which three nematodes (roundworms) directly penetrate the skin with their infectious larvae?
- S. stercoralis
- N. americanus
- A. duodenale
Which three nematodes (roundworms) ingest contaminated soil?
- E. vermicularis
- T. trichiuria
- A. lumbricoides
Match the Cestode term to the definition…
____: Structure on anterior end of worm with suckers (+/- hooks) that functions to attach the worm to the intestinal cell wall
_____: Body of tapeworm; composed of many segments called proglottids
_____: Segments, each of which contains a complete set of sex organs (both M/F); can break off and pass out of body into stool
A. Scolex
B. Strobila
C. Proglottids
A. Scolex: Hooks on anterior end
B. Strobila: Tapeworm body
C. Proglottids: Segments that contain sex organs
_____: Mature, egg filled proglottids, located at posterior end of organism
____: Cysts formed by larvae embedded in body tissues
A. Cysticerci
B. Gravid Proglottids
B. Gravid Proglottids: Mature, egg filled proglottids, located at posterior end of organism
A. Cysticerci: Cysts formed by larvae embedded in body tissues
Which part of Cestodes are important for attachment? reproduction?
Attachment - Scolex
Reproduction - Proglottids
What three features of Cestodes can you used to differentiate them?
- Eggs
- Scolex
- Proglottids
True or False: The eggs of e. saginata and T. solium are indistinguishable from one another
True
- Both have radial striations on shell
Which of the following has four suckers and NO hooks?
A. T. solium scolex
B. T. saginata scolex
B. T. saginata scolex
Which of the following has four suckers and is “armed” with hooks (rostellum)?
A. T. solium scolex
B. T. saginata scolex
A. T. solium scolex
How do the gravid proglottids of T. saginata compare to those of T. solium?
T. saginata
- 12 to 20 uterine branches
T. solium
- 5 to 10 uterine branches
Describe the D. latum ova and gravid proglottid:
Ova
- operculum
- polar knob on opposite ends of egg
Gravid Proglottid
- rosette shaped uterine branches
Which of the following scolex has two grooved suckers, one on each side of the scolex?
A. T. saginata
B. T. solium
C. D. latum
C. D. latum
____ is the definitive host of T. saginata while ____ is the intermediate host of T. saginata
Human = definitive host
Cow = intermediate host
In T. saginata, cow will ingest embryonated eggs. Larvae migrate to tissues to become ____
cysticerci
How can humans become infected with T. saginata?
Ingestion of raw or undercooked beef
- Upon consumption, stomach acids release of cysticerci from muscle tissue
- Scolex attaches to intestinal wall + growth
- Proglottids passed in feces
Life cycle of T. solium is similar to T. saginata, except in the case of T. solium ___ (intermediate host) eats embryonated eggs
Pig - intermediate host
Human - definitive host
What structure can you identify in feces to diagnose T. solium or T. saginata?
Proglottids
In D. latum, larvae hatch in the water and ___ eats them. Following this, minnow eat infected ____. Larger fish eats infected minnow.
copepod (small crustacean)
True or False: Pleurocercoid larva are ingested with infected raw fish in D. lactum
True
When D. latum infection occurs, scolex of____ attaches to mucosa.
Where does gravid proglottid break up?
pleurocercoid
colon
True or False: With D. latum infection, usually you will see eggs in feces (not intact proglottid)
True
Where are D. latum eggs deposited (where they will eventually hatch)?
Water
Definitive vs. Intermediate host of D. latum?
Human - definitive host
Fish - intermediate host
True or False: In D. latum infection, pleurocercoid larva is ingested with infected raw fish
True
Cysticercosis is an invasive human disease in humans, which can produce cysticerci in brain, eye, and muscles.
One can only develop this infection, however, if they ingest embryonated ____ eggs – in this case: human is intermediate (dead end) host
A. T. solium
B. D. latum
C. T. saginata
A. T. solium
Compare and contrast disease manifestation (Cysticercosis vs. Taeniasis) in T. solium:
What are the main signs and symptoms associated with Cestodes (tapeworms)?
- Usually no symptoms!
1) Cysticercosis
- Occulocysticercosis: blindness
- Neurocysticercosis: seizures
2) D. latum can cause pernicious-like anemia