38 - Tapeworm and Fluke Infections of the GI Tract Flashcards
A seven-year-old child was taken to the doctor for abdominal pain, gas, bloating and intermittent diarrhea. The symptoms started about two days after returning from summer camp. Stool specimens were collected in formalin and polyvinyl alcohol (PVA) and sent to a commercial lab for ova-and-parasite (O&P) examination. Figures A-F show what was observed on a trichrome-stained smear made from the PVA-preserved stool. The images were captured at 1000x magnification. What is your diagnosis? Based on what criteria?
Giardia
Key: abdominal pain, gas, bloating and intermittent diarrhea
What are cestodes?
Tapeworms
There are three basic structures of adult tapeworms. What are they?
- Scolex
- “Neck”
- Body (strobila)
What is the scolex of an adult tapeworm?
The rounded head of the worm, usually armed with hooks and/or suckers
What is the “neck” of the adult tapeworm?
The area from which new body segments are generated
What is the body (strobila) of the adult tape worm?
A long SEGMENTED structure - individual segments are called proglottids
What does it mean to say that humans are the “definitive host” of tape worms?
Some adult tapeworms reside in the GI tract of the host… Typically the small intestine
Which tapeworms are an example of having humans as the definitive host?
- Taenia saginata (beef tapeworm)
- Taenia solium (pig tapeworm)
- Diphyllobothrium latum (fish tapeworm)
What does it mean to say that humans are the “intermediate host” of tape worms?
Some adult tape worms are present in different larval stages in various tissues in the body
Which tapewomrs are an example of having humans as an intermediate host?
- Echinococcus granulosus (dog tapeworm)
- Taenia solium (pig tapeworm)
How is the beef tapeworm transmitted?
Ingestion of undercooked beef containing encysted larvae
How many adult worms are humans generally infected with?
A single worm
How large do beef tapeworms (saginata) get?
10-30 feet long
They can live up to 25 years
What are the symptoms of beef tapeworm (saginata)?
Generally asymptomatic
- Mild abdominal pain
- Feeling of “fullness”
How do you diagnose beef tapeworm (saginata)?
Identification of proglottids or eggs that are found in the stool of an infected individual
How do you prevent beef tapeworm (saginata)?
- Prevent cattle from becoming infected
- Eliminate contact with infected cattle
- Prevent human infection by cooking meat thoroughly
What do we commonly call Taenia solium?
Pork tapeworm
Which is more common pork or beef tapeworm?
Beef tapeworm (saginata) is more common
Pork tape worm (solium) is less common
These are the trends in the US AND worldwide
How do you transmit Taenia solium (pork tapeworm)?
Ingestion of undercooked pork containing cycsts that result in intestinal disease
Ingestion of embryonated eggs will result in extra-intestinal disease (cysticercosis)
What is the intestinal disease of pork tapeworm similar to?
Beef tapeworm
What is an extra-intestinal disease caused by the Taenia solium (pork tapeworm) called?
Cysticercosis
What is the disease process of Cysticercosis?
Ingested eggs hatch in intestine and release infectious larvae which enter the circulation and travel to various body sites where they encyst.
What does this induce?
Cysticercus creates a space filling lesion and induces localized inflammation.
Where can you see this happening?
Striated muscle, heart, brain, eyes
Which form will you see the most severe complications with?
Neurocysticercosis
What complications would you see?
Seizure and neurological defects
How many cases do we see each year in the US of Neurocysticercosis?
2000