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Enterobius vermicularis

Enterobius vermicularis. Taxonomical position. Phylum : Nematoda Class : Secernentea Order : Oxyurida Super family : Oxyuroidea Family : Oxyuridae Genus : Enterobius Species : vermicularis. Common names:. Pin worm

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Enterobius vermicularis

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  1. Enterobius vermicularis

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

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

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

  5. Morphology: 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

  6. MALE WORM: • Posterior end is curved • Copulatory spicule • Length : 2-5 mm • Thickness : 0.1- 0.2 mm • Life span : 7 weeks

  7. FEMALE WORM: • Thin, pointed, pin like tail • Reproductive organs - T shaped - paired • OVIPAROUS • Length : 8 - 13 mm • Thickness: 0.3 - 0.5 mm • Life span : 5 - 13 weeks

  8. 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

  9. LIFE CYCLE

  10. 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

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

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

  13. Conti… • 1 worm = 5000 – 17000 eggs • Become infective in 6 hrs • Completes life cycle in 2 weeks – 2 months

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

  15. 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

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

  17. 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

  18. 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

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

  20. Treatment: • Single dose: Pyrantel - 11mg/kgwt Mebendazole - 100mg/kgwt Albendazole - 400mg/kg wt • Piperazine - 65mg / kg wt – 1 week • Pyrantel causes spastic paralysis of the worm

  21. Prophylaxis: • Health education on personal hygiene • Group chemotherapy

  22. THANK YOU

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