1. Enterobius vermicularis

2. Taxonomical position Phylum : Nematoda Class : Secernentea
Order : Oxyurida
Super family : Oxyuroidea
Family : Oxyuridae
Genus : Enterobius
Species : vermicularis

3. ‘Leukart’ – first described the complete life cycle in 1865
Common names:
Pin worm
Thread worm
Seat worm
History:
‘Leukart’ – first described the complete life cycle in 1865

4. Distribution: Habitat: Cosmopolitan
More common in temperate and cold climate than warm climate
Habitat:
LARGE INTESTINE
- Caecum
- Appendix
- Ascending colon

6. Morphology: Cervical Alae: - At the anterior end ADULT:
Short, white, fusiform
Pointed ends
Resemble white threads
Cervical Alae:
- At the anterior end
- Three in number
- Wing like cuticular expansions
- Transversely striated
Oesophagus- DOUBLE BULB

7. MALE WORM: Posterior end is curved Copulatory spicule Length : 2-5 mm
Thickness : mm
Life span : 7 weeks

8. FEMALE WORM: Thin, pointed, pin like tail Reproductive organs
- T shaped
- paired
OVIPAROUS
Length : mm
Thickness: mm
Life span : weeks

9. EGG: Colourless, non-bile stained Shape: Planoconvex
Shell : Double layered
Transparent
Sticky outer albuminous layer
Contains ‘tadpole shaped’,
coiled larva
Viable up to 2 weeks

10. LIFE CYCLE

12. Life cycle: Simplest of all the intestinal worms Host :
MONOXENOUS- single host – Human
Infective form: embryonated egg
Route: Faeco-oral transmission
Eggs transform in to larvae in 5 weeks in small intestine
Larva undergo moulting in ileum and finally mature in to adult in caecum with in 15 to 30 days
Male dies after fertilization

13. Conti… Egg 5 weeks (small intestine) Larva moulting(ileum)
15-30 days maturation(caecum)
Adult
male female
dies after fertilization

14. Conti… migrate to rectum come out through anus during night time
Eggs laid on perineal, peri anal skin

15. Conti…
1 worm = – eggs
Become infective in 6 hrs
Completes life cycle in 2 weeks – 2 months

16. Pathogenesis: Adult worm: Egg: - mucoid secretions – adherence of egg
- irritation
- Characteristic NOCTURNAL PERINEAL / PERIANAL
ITCHING

17. Clinical manifestations:
ENTEROBIASIS – Pruritis ani
Scratching, excoriation of skin
Disturbed sleep, irritability, nocturnal enuresis, weight loss, abdominal pain
Severe infection:
Neurosis
Nail biting
Grinding teeth at night

18. Complications: Vulvo- vaginitis Chronic salpingitis Prostatitis
Urethritis
Endometritis
Granulomata with dead worms, eggs

19. Epidemiology: Group infection: School children
Prevalent in temperate countries
USA, European countries
Source: Infected humans
others like bedding, night clothing, table tops,
door knobs,taps etc.,
Transmission: Auto infection
contaminated articles / direct contact
inhalation of eggs
Retroinfection

20. Diagnosis: H/O perianal pruritis LAB DIAGNOSIS:
Demonstration of Adult worm:
- On the surface of stool sample
- On the perianal skin
- In the stool after an enema
Demonstration of Eggs:
- As they are seldom excreted in faeces, stool sample
is not useful for diagnosis

21. 3.Dirt from finger nails. 1. NIH swab: 2.Scotch tape swab:
Atleast 3 specimen collected
in 3 consecutive days
3.Dirt from finger nails.

22. Treatment: Single dose: Pyrantel - 11mg/kgwt Mebendazole - 100mg/kgwt
Albendazole mg/kg wt
Piperazine - 65mg / kg wt – 1 week
Pyrantel causes spastic
paralysis of the worm

23. Prophylaxis:
Health education on personal hygiene
Group chemotherapy

24. THANK YOU