Pinworm, or Enterobius vermicularis, is a common parasitic worm that infects the human large intestine. The adult female worm lives in the caecum and colon and lays thousands of eggs per night around the anal area. The eggs are infectious within 6 hours of being laid and can remain viable for up to 2 weeks in moist conditions. People become infected by ingesting the eggs, often through hand-to-mouth contact. The life cycle is direct with no intermediate host. Pinworm infection is most common in children and can cause symptoms like anal itching and sleep disturbance.

3. Order:Oxyurida
Super family:Oxyuroidea
Family:Oxyuridae
Genus:Enterobius
Species:E.vermicularis.

4. COMMON NAME :PIN WORM
SEAT WORM
THREAD WORM

5. HISTORY & DISTRIBUTION

6. HABITAT: Caecum, appendix, adjacent
portion of ascending colon.
MORPHOLOGY
EGG
ADULT
WORM

7. • Colorless &not bile stained.
• Floats in saturated salt solution.
• Elongated ovoid with planoconvex
• Double layered egg shell,relatively
thick& transparent.
• Outer albuminous layer makes egg
sticky.
• Egg contains fully formed tadpole-
shaped coiled embryo-infectious only 6
hrs after being deposited on the skin.
• Moist conditions-viable for 2 wks.
• Single female worm lay 5000-
17000eggs.
EGG

8. Adult worm common features:
1.Mouth is surrounded by 3 wing like cervical alae.
2.Esophagus has a double bulb structure.
Female worm
O 8-13 mm long,0.3-0.5mm
thick.
O Posterior 1/3^rd drawn
into pointed pin-like tail.
O Vulva located in front of
middle 1/3^rd of body
opens into single vagina
which leads to paired uteri,
oviducts and ovaries.
O Gravid female, whole body
filled by distended uteri
carrying 1000s of eggs.
O Survive for 5-12 wks.

10. LIFE CYCLE
• MONOXENOUS ,entire life cycle in human host.
• Has no intermediate host.
• Does not undergo systemic migration.
• Natural host:man
• Infective form:embryonated eggs containing infective larva.
• Mode of infection
 Ingesting embryonated eggs means of
 contaminated fingers
 autoinfection

12. RETRO INFECTION
 Mode of infection from anus to colon.
 Eggs laid on the perianal skin immediately
hatch into infective stage of larva
 Migrates through the anus and develops into
worms in the colon.

13. Dies
after
mating
.

14. When all eggs are laid female worm dies
Worm retreat into anal canal and come out
again to lay eggs.
Female may reach upto vulva, vagina uterus,
fallopian tube,sometimes peritoneum.
Gravid female migrates down the colon to
rectum.
Worm comes out crawls on the perianal
&perineal skin to lay sticky eggs
GRAVID FEMALE WORM
?????

15. PATHOGENICITY &CLINICAL FEATURES
 Enterobiasis
occurs
mostly in
children.
 More
common in
females.
 1/3^rd
infection are
asymptomati
c.

16. PRURITIS ANI
DISTURBS
SLEEP
NOCTURNAL
ENURESIS
CLINICAL FEATURES

17.  Worm crawl into vulva &
vagina causing irritation and
mucoid discharge.
 May migrate to uterus,fallopian
tube,peritoneum causing
chronic salpingitis,
cervicitis,
peritonitis,recurrent UTI.
APPENDICITIS