3.2 - ENTEROBIUS VERMICULARIS Flashcards
(38 cards)
other name for E. vermicularis
Oxyuris vermicularis
common names
pin worm, society worm, seat worm
most common helminth parasite found in crowded and temperate areas
Enterobius vermicularis
Final host
man
habitat
large intestine (cecum)
mode of transmission
ingestion, retroinfection, inhalation, autoinfection
infective stage
embryonated egg
diagnostic stage
egg, adult worm
unique diagnostic feature
- cephalic alae - lateral wings
- esophageal bulb
- 2-5 mm
- curved tail and single spicule
male adult
- 8-13 mm
- pointed posterior end lays 15,000 eggs
female adult
- light yellowish white
- meromyarian muscle arrangement
general morphology
- colorless, ovoid with one side flattened
- measures 20-30um wide by 50-60 um long
eggs
shape of eggs
D-shaped
outer egg layer
albuminous layer
provides mechanical protection
inner egg layer
embryonic lipoidal membrane
provides chemical protection
eggs can survive ? into the environment
2-3 weeks
embryonation of eggs takes ?
4-6 hours
life cycle
- mouth
- small intestine
- large intestine
- copulation (adult male and female)
- perianal region (deposition of eggs)
- random objects
- other members would be in contact, eggs could float
- accidentally ingest and inhale
- new host
Once someone has ingested pinworm eggs, there is an incubation period of ? or longer for the adult gravid female to mature in the small intestine
1 to 2 months
Males usually die after
copulation
Females usually die after
egg deposition
eggs from the perianal region are accidentally ingested by the same person
Autoinfection
when eggs in the perianal region hatch and the larva crawls back up into the intestine or intestinal tract
Retroinfection