Cestodes Flashcards
Cestodes can have a scolex (head) with suckers, some with hooklets (“armed”); ________ (segments) can be diagnostic for some
Proglottids
Cestodes are a type of _______ (members of platyhelminth)
Flatworms
An entire chain of proglottids
Strobila
What portion of cestodes are passed in the stool?
Eggs or proglottids
What is the most common tapeworm in the US?
Hymenolepis nana
Hymenolepis nana:
- common name
Dwarf tapeworm
Hymenolepis nana:
- most common in what age group of people
More common in children
Hymenolepis nana:
- intermediate host
No intermediate host or may have arthropod intermediate (flea or beetle)
Hymenolepis nana:
- how is it spread
Fecal oral route, or by ingestion of infected arthropod
Hymenolepis nana:
- major clinical manifestation
Usually asymptomatic
Hymenolepis nana:
-microscopic appearance of egg
Thin shelled egg in stool with hexacanth embryo, polar thickenings and filaments
Hymenolepis nana:
- adult’s appearance
Small, tiny armed scolex, hooklets
Hymenolepis diminuta:
- common name
Rat tapeworm
Hymenolepis diminuta:
- intermediate host
Rat is definitive host, humans ingest infected arthropod (meal beetles, fleas)
Hymenolepis diminuta:
- microscopic egg appearance
Eggs found in stool, hexacanth embryo with no polar filaments; eggs are larger and thicker shelled then E. nana
Diphyllobothrium latum:
- common name
Broad fish tapeworm
Diphyllobothrium latum:
- where is it found?
Temperate zones (even Scandinavia) found in U.S. (northern Midwest lakes)
Diphyllobothrium latum:
- intermediate host
To intermediates: copepod and freshwater fish
Diphyllobothrium latum:
- claim to fame
Only operculate tapeworm found in man
Diphyllobothrium latum:
- most important clinical manifestation
Megaloblastic anemia (competition for B12)
Diphyllobothrium latum:
- microscopic appearance of eggs
Eggs or proglottids passed in the stool; eggs are operculate, shoulders, aboperculate knob
Diphyllobothrium latum:
- proglottid appearance
Proglottids are broader than long (often chain of proglottids past)
Taenia saginata:
- common name
Beef tapeworm
Taenia saginata:
- intermediate host
Cattle
Taenia saginata:
- where is it found
Worldwide but rare in the US
Taenia saginata:
- clinical manifestations
Vague GI symptoms
Taenia saginata:
- microscopic egg appearance
Striated shell, hexacanth embryo (can’t differentiate from T. solium)
Taenia saginata:
- proglottid appearance
Proglottids are longer than wide (15 to 20 uterine branches)
Taenia solium:
- common name
Pork tapeworm
Taenia solium:
- intermediate host
Pig
Taenia solium:
- what are the two types of infections
- Larvae infection- intestinal
- Egg ingestion Cysticercosis (very serious)
Cysticercosis:
- cysticerci (“_______ worm”): larvae in fluid filled _______
Bladder
What is the number one cause of adult onset epilepsy in endemic areas
Cysticercosis (cysticerci can locate in brain, eye, muscle; headaches, seizures, psychiatric disturbances can result)
Taenia solium:
- microscopic appearance of eggs
Eggs can’t be differentiated from T. saginata
Taenia solium:
- proglottid appearance
Similar to T. saginata except 7 to 13 uterine branches
Echinococcus granulosus:
- common name
Canine tapeworm
Echinococcus granulosus:
- what disease does it cause
Hydatid Cyst Disease (cystic disease)
Echinococcus granulosus:
- intermediate host
Sheep/sheep dogs (occur often in sheep grazing countries, including U.S.)
Echinococcus granulosus:
- diagnosis
Cysts grow in liver, lungs, brain;
- aspirate fluid from the cyst; cyst will contain numerous scolices and hooklets (“hydatid sand”)
Dipylidium caninum:
- common name
Dog tapeworm
Dipylidium caninum:
- how is it spread
Children accidentally ingested dog fleas with tapeworm (usually asymptomatic)
Dipylidium caninum:
- egg appearance
Egg packets (numerous hexacanth embryo)
Dipylidium caninum:
- proglottids appearance
Resemble cucumber seeds or rice grains
