GI Helminths

Question 1

nematode (morph, sex, intermediate host)

Answer 1

morph: cylindrical/spindle
sex: separate sexes
host: variable

Question 2

cestode (morph, sex, intermediate host)

Answer 2

morph: flattened/segmented
sex: herm
host: one

Question 3

trematode (morph, sex, intermediate host)

Answer 3

morph: leaf-shaped
sex: herm
host: two

Question 4

intestinal nematodes

Answer 4

ascaris lumbricoides (roundworm)
enterobius vermicularis (pinworm)
trichuris trichiura (whipworm)
necator americanis, ancylostoma duodenale (hookworms)
strongyloides stercoralis (threadworm)

Question 5

tissue-dwelling nematodes

Answer 5

toxicara canis
trichinella spiralis
anisakis

Question 6

cestodes

Answer 6

taenia aginata
taenia solium
hymenolepis nana
diphylobothrium latum
echinococcus

Question 7

trematodes

Answer 7

clonorchis sinensis

paragonimus westermani

Question 8

worm burden

Answer 8

# adult worms
usually constant in host
exception: strongloides

Question 9

nematode characteristics

Answer 9

cylindrical/unsegmented
can survive in host for months to years
immune response to infection

Question 10

ascaris lumbricoides description

Answer 10

roundworm
15 - 30 cm
pinkish-white

Question 11

most common nematode infection worldwide

Answer 11

ascaris lumbricoides

Question 12

ascaris lumbricoides life cycle

Answer 12

ingest mature eggs (2-3 weeks)
hatch in SI 
penetrate --> liver --> lungs
cough/swallow 
mature to adults in SI
eggs in stool

Question 13

ascaris lumbricoides clinicals

Answer 13

Migration: cough, pneumonitis, eosinophilia Gut: pain, obstruction DEPEND ON WORM BURDEN

Question 14

enterobius vermicularis description

Answer 14

pin worm
m: 2-5 mm/f: 8 - 13 mm
whitish yellow

Question 15

enterobius vermicularis life cycle

Answer 15

ingest mature eggs (1-2 hrs)
mature in cecum - mate
deposit eggs outside anus

Question 16

enterobius vermicularis transmission

Answer 16

ingest mature eggs (1-2hrs)

• person-to-person
• re-infection
• airborne

Question 17

enterobius vermicularis clinicals

Answer 17

minimal pathology anal puritis
recover eggs with cellophane tape
common in school age kids

Question 18

trichuris thrichiura description

Answer 18

whip worm
4 cm
feed on secretions (not blood)

Question 19

trichuris thrichiura life cycle

Answer 19

ingest mature eggs (10 - 30 days
eggs hatch in cecum
mature in colon
eggs in feces

Question 20

trichuris thrichiura clinicals

Answer 20

Light: may be asymptomatic; Heavy: eosinophilia, dysentery, weight loss, rectal prolapse
most common in kids

Question 21

necator americanis description

Answer 21

hookworm
1 cm
plates to attach
feed on blood

Question 22

necator americanis life cycle

Answer 22

mature larvae penetrate skin (9 days)
blood --> lungs
cough/swallow
adults attach to SI
eggs in feces

Question 23

necator americanis clincals

Answer 23

iron deficient anemia, Penetration: dermatitis/puritus ; Migration: cough/eosinophilia

Question 24

ancylostoma duodenale description

Answer 24

hookworm
1 cm
teeth to attach
feed on blood

Question 25

ancylostoma duodenale life cycle

Answer 25

``` mature larvae penetrate skin (9 days) blood --> lungs cough/swallow adults attach to SI eggs in feces ```

Question 26

ancylostoma duodenale clinicals

Answer 26

iron deficient anemia, Penetration: dermatitis/puritus ; Migration: cough/eosinophilia

Question 27

strongyloides stercoralis description

Answer 27

Thread worm | smallest GI nematode - 2mm

Question 28

strongyloides stercoralis life cycle

Answer 28

larvae penetrate skin blood --> lungs cough/swallow adults in SI eggs (internal or external) mature to larvae do cycle again (penetrate SI wall or perianal skin)

Question 29

strongyloides stercoralis clinicals

Answer 29

may be asymptomatic; Migration: pneumonitis; Gut: pain, diarrhea; life threatening for immunocomp

Question 30

toxocara canis vector

Answer 30

dogs

Question 31

toxocara canis life cycle

Answer 31

ingest eggs eggs hatch in intestines penetrate - circulation various tissues - never mature

Question 32

toxocara canis clinicals

Answer 32

Hypereosinophilia Visceral larval migrans: liver (hepatomegaly), lungs, brain, heart; Ocular larval migrans: eye --> inflammation, blindness

Question 33

trichinella spiralis vector

Answer 33

rats and swine

Question 34

trichinella spiralis life cycle

Answer 34

``` ingest cyst (undercooked pork) excyst in guut adults in SI larvae to blood to striated muscle encyst ```

Question 35

trichinella spiralis clinicals

Answer 35

Mild GI symptoms; Migration/Encystment: fever, myalgia, rashes

Question 36

anisakis description

Answer 36

round worm of fish

Question 37

anisakis life cycle

Answer 37

ingest encysted larvae (in undercooked fish) excyst in stomach larve in stomach, maybe SI

Question 38

anisakis clinicals

Answer 38

violent abdominal pain, nausea, vomiting | SI --> imitate Crohns

Question 39

pathology of cestodes due to

Answer 39

larval phase | adults confined to gut

Question 40

taenia saginata description

Answer 40

beef tapeworm 30 ft use scolex to attach to SI live up to 30 years

Question 41

taenia saginata life cycle

Answer 41

ingest cysticerus (encysted larve) from undercooked beef adult in SI eggs in feces

Question 42

taenia saginata clinicals

Answer 42

asymptomatic or mild GI symptoms | taeniasis

Question 43

taenia solium description

Answer 43

pork tapeworm | 10 ft

Question 44

taenia solium life cycle

Answer 44

1. ingest cysticercus in undercooked pork adult in SI 2. ingest eggs become cysticercus in tissue (muscle, brain, eye)

Question 45

taenia solium clinicals

Answer 45

1. taeniasis: asymptomatic or mild GI symptoms 2. cysticerosis: small # is asymptomatic, large # --> inflammtory rxn, fever, muscle pain, eosinophilia, neurologic abnormalities, seizures, neurocysticerosis

Question 46

hymenolepis nana description

Answer 46

dwarf tapeworm smallest TW - 15 - 40 mm adults live 4 - 6 weeks no intermediate host needed

Question 47

most common human TW in US

Answer 47

hymenolepis nana

Question 48

hymenolepis nana life cycle

Answer 48

ingest eggs in contaminated food/water adults in SI eggs in stool some mature and penetrate SI

Question 49

hymenolepis nana clinicals

Answer 49

often asymptomatic; Heavy: pain, diarrhea, weight loss

Question 50

diphyllobothrium latum description

Answer 50

fish tapeworm largest TW (> 10 m) crustaceans and fish as host

Question 51

diphyllobothrium latum life cycle

Answer 51

ingest larvae in undercooked fish | adult in SI

Question 52

diphyllobothrium latum clinicals

Answer 52

may be asymptomatic; abdominal discomfort, diarrhea, vomiting, weight loss, vit B12 deficient anemia, intestinal obstructuion

Question 53

echinococcus life cycle

Answer 53

ingest eggs larvae in SI wall to liver to lungs to CNS or bone

Question 54

echinococcus clinicals

Answer 54

hydatid cysts: fluid filled around larvae (2L) --> pressure damage to organs; anaphylaxis due to ruptured cysts

Question 55

clonorchis sinensis description

Answer 55

chinese liver fluke Asian snail/fish hosts

Question 56

clonorchis sinensis life cycle

Answer 56

ingest encysted larvae (metacercariae) excyst in duodenum migrate directly to biliary ducts

Question 57

clonorchis sinensis clinicals

Answer 57

liver damage | gallstones (high worm burden)

Question 58

paragonimus westermani description

Answer 58

Asian live 65 - 90 days snails/crustacean hosts

Question 59

paragonimus westermani life cycle

Answer 59

ingest encysted larvae (metacercariae) excyst in duodenum directly invade lungs

Question 60

paragonimus westermani clinicals

Answer 60

acute (invasion/migration): diarrhea, abdominal pain, cough, fever; chronic (pulmonary): cough, expectoration of discolored mucous, abnormal chest radiographs