GI Helminths Flashcards
nematode (morph, sex, intermediate host)
morph: cylindrical/spindle
sex: separate sexes
host: variable
cestode (morph, sex, intermediate host)
morph: flattened/segmented
sex: herm
host: one
trematode (morph, sex, intermediate host)
morph: leaf-shaped
sex: herm
host: two
intestinal nematodes
ascaris lumbricoides (roundworm) enterobius vermicularis (pinworm) trichuris trichiura (whipworm) necator americanis, ancylostoma duodenale (hookworms) strongyloides stercoralis (threadworm)
tissue-dwelling nematodes
toxicara canis
trichinella spiralis
anisakis
cestodes
taenia aginata taenia solium hymenolepis nana diphylobothrium latum echinococcus
trematodes
clonorchis sinensis
paragonimus westermani
worm burden
# adult worms usually constant in host exception: strongloides
nematode characteristics
cylindrical/unsegmented
can survive in host for months to years
immune response to infection
ascaris lumbricoides description
roundworm
15 - 30 cm
pinkish-white
most common nematode infection worldwide
ascaris lumbricoides
ascaris lumbricoides life cycle
ingest mature eggs (2-3 weeks) hatch in SI penetrate --> liver --> lungs cough/swallow mature to adults in SI eggs in stool
ascaris lumbricoides clinicals
Migration: cough, pneumonitis, eosinophilia Gut: pain, obstruction DEPEND ON WORM BURDEN
enterobius vermicularis description
pin worm
m: 2-5 mm/f: 8 - 13 mm
whitish yellow
enterobius vermicularis life cycle
ingest mature eggs (1-2 hrs)
mature in cecum - mate
deposit eggs outside anus
enterobius vermicularis transmission
ingest mature eggs (1-2hrs)
- person-to-person
- re-infection
- airborne
enterobius vermicularis clinicals
minimal pathology anal puritis
recover eggs with cellophane tape
common in school age kids
trichuris thrichiura description
whip worm
4 cm
feed on secretions (not blood)
trichuris thrichiura life cycle
ingest mature eggs (10 - 30 days
eggs hatch in cecum
mature in colon
eggs in feces
trichuris thrichiura clinicals
Light: may be asymptomatic; Heavy: eosinophilia, dysentery, weight loss, rectal prolapse
most common in kids
necator americanis description
hookworm
1 cm
plates to attach
feed on blood
necator americanis life cycle
mature larvae penetrate skin (9 days) blood --> lungs cough/swallow adults attach to SI eggs in feces
necator americanis clincals
iron deficient anemia, Penetration: dermatitis/puritus ; Migration: cough/eosinophilia
ancylostoma duodenale description
hookworm
1 cm
teeth to attach
feed on blood