3.2 - ENTEROBIUS VERMICULARIS Flashcards
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
female adult lays
15,000 eggs
Enterobius infection
Enterobiasis or oxyuriasis
- nocturnal pruritus ani
- local irritation of the vagina
- inflammation of the intestinal wall
- formation of granuloma
- salpingitis
pathogenesis and clinical manifestations
most sensitive diagnostic test
cellulose tape technique
clearing agent for cellulose tape technique
toluene
when to perform cellulose tape technique?
- late at night
- first thing in the morning before bathing or defecation
Adult worms can only deposit eggs ?
late at night
? of cases are detected using routine stool examination
5%-10%
Before releasing results, it should be conducted on ?
3 consecutive mornings
types of perianal swabs
- National Institute of Health Swab
- Swellen Grebel Swab
- Scotch Tape Graham’s
- Petroleum Coated Swab
type of perianal swab that uses cellophane
National Institute of Health Swab
type of perianal swab that uses a pestle moistened with water
Swellen Grebel Swab
- Common within families with school-aged children, in primary caregivers of infected children, and in institutionalized children
- Only intestinal nematode that cannot be controlled through sanitary disposal of human feces
- Infection through close contact
epidemiology
treatment
albendazole
