Ascaris lumbricoides: The Largest Intestinal Nematode Parasite
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One of the most common parasitic infections in India
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Ascaris lumbricoides: The Largest Intestinal Nematode Parasite
- 2. Ascaris • k/a round worm • Largest nematode parasite in human intestine • Lumbricodes = Earthworm • Distributed world wide • Lives in small intestine
- 3. Morphology • Large cylindrical worms with tapering ends • Anterior end is more pointed • Pale pink or flesh colored when inside the body • White outside the body • Mouth 3 fine denticulated lips – One dorsal – Two ventero lateral
- 4. Differentiate Male • 15-30cms in length • 2-4mm thick • Posterior end curved to form hook • 2 copulatory spicules Female • 20-40cms in length • 3-6 mm thick • Posterior end straight and conical • Vulva is placed mid ventrally in genital girdle or vulvar waist at the junction of anterior and middle 1/3 rd of the body • Vulva leads to single vagina • Single vagina leads to 2 genital tubules
- 7. Beauty of the Worm! • 27 million eggs • 2,00,000 eggs/ day • Eggs passed in feces • Fertilized / embryonated eggs – infective • Unfertilized / non embryonated eggs – Non infective
- 8. Fertilized eggs! • Spherical / ovoid • Bile stained • Floats in salt solution • 60-75 x 40-50nm • Enclosed in shell – Outer coarse mamillated albuminous coat – Thick transparent middle – Inner lipoidal vitelline membrane • Large unsegmented ovum • Coarse lecithin granules • Ovum fully fills the egg except the cresenteric pole
- 9. Unfertilized eggs! • Longer • Elliptical • Thin shell • Scanty irregular albumin • Ovum atrophic • Heavy and sinks in salt solution
- 10. Life cycle!
- 11. Inside man!
- 12. Clinical features! • Due to larval migration – Allergic reaction infiltration of eosinophils, macrophages and epitheloid cells pneumonia • Low grade fever, dry cough, asthmatic wheezing, urticaria, eosinophilia, mottled lung • Sputum charcot leyden crystals • Larvae in sputum • More in gastric washings Loeffler’s syndrome
- 13. Clinical features! • Due to adult worms – Spoliative / Nutritional effects • Heavy worm infestation > 500 worms • Interfere with absorption – PEM – VIT A • Loss of appetite • Listless • Alteration in jejunal mucousa and shortening of villi
- 14. Clinical features! • Due to adult worms – Toxic effects • Due to hypersensitivity to worm antigens – Fever – Urticaria – Angioneurotic edema – Wheezing – conjunctivitis
- 15. Clinical features! • Due to adult worms – Mechanical effects • Reflex peristalsis • Recurrent severe abdominal pain • Clumps to mass – Volvulus – Intussusception – Intestinal obstruction
- 16. Wanderers! • Biliary tract • Pancreas • Liver abscess • Oesophagus – Nose – Mouth • Trachea – Respiratory obstruction – Lung abscess • Appendix • Peritonitis – Weak spots
- 17. Diagnosis • Larvae in sputum • Larvae in gastric washings • Charcot leyden crystals • Eosinophilia • Demo of egg in feces • Worm passing out • Skin test with ascaris antigen not very effective • Barium contrast radiography
- 23. Treatment • Pyrantel pamoate • Albendazole • Mebendazole • Piperazine citrate
- 24. Prevention • Night soil • Iodine 200ppm irrigation for 15mins
- 25. Thank you!!