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Ascaris lumbricoides

Ascaris lumbricoides. Beth Wozney. The largest nematode to infect the human intestine. Taxonomy. Kingdom: Animalia Phylum: Nematoda Class: Rhabditea Order: Ascaridida Family Ascarididae Genus: Ascaris Species: lumbricoides. Geographic Distribution.

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Ascaris lumbricoides

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  1. Ascarislumbricoides Beth Wozney

  2. The largest nematode to infect the human intestine..

  3. Taxonomy • Kingdom: Animalia • Phylum: Nematoda • Class: Rhabditea • Order: Ascaridida • Family Ascarididae • Genus: Ascaris • Species:lumbricoides

  4. Geographic Distribution • Up to ONE BILLION people wolrdwide are infected. • Both tropical and temperate areas • More common in tropical and subtropical • In the United States? • South Eastern states • Children are most commonly infected

  5. Morphology 15-35 cm long and the diameter of a lead pencil Female: straight posterior Male: curved posterior (button-hook tail)

  6. Morphology Both male and female have three anterior lips with small, tooth-like projections.

  7. Morphology • Fertile eggs: 45-75 um by 35-50 um • Thick hyaline wall around a one cell-stage embryo • Brown, bile colored outer layer • Decorticated: no mammillated outer coat • Unfertile Eggs: up to 90 um • Elongated with mass of highly refractile granules.

  8. Life Cycle

  9. Life Cycle • Definitive host: • Humans • Adult worms: • Live in lumen of the small intestine • Female can produce 200,000 eggs/day • Passed in the feces

  10. Life Cycle • Eggs: in the environment • Unfertilized: not infective • Fertilized: embryonate • Infective after about 18 days depending on the environment • Optimum: Moist, warm, shaded soil

  11. Life Cycle • Human ingests infected egg (Fecal-Oral Route) • Larvae hatch inside the human host • Invade intestinal mucosa: • Carried through systemic circulation to the lungs • Larvae mature here (10-14 days) • Penetrate aleveolar walls into the throat • Swallowed! • Small intestine: Adults

  12. Dum Dum Dum… • http://www.indyarocks.com/videos/Why-is-eating-dirt-is-bad-Ascaris-lumbricoides-2296565

  13. For Your Information… • It takes 2-3 months from ingestion of the fertilized (infectious) egg to mature into the adult female. • Adult worms can live 1-2 years. • Sometimes, it is found concurrently with whipworm. • Both are soil-transmitted helminth infections?

  14. Pathogenesis • Ascarislumbricoides causes ascariasis: • Adults: abdominal discomfort, loss of appetite, and pain • Intestinal obstruction • Affects growth of children • Exit: mouth, tear duct, nose • Fever? Invades other organs • Liver abscess • Peritonitis • Secondary infection in the lungs • Larva: Loffler syndrome • Asthma, edema, pneumonitis, and eosinophilic infiltration

  15. Diagnosis • Diagnosis: • The egg in a stool sample • X-ray: bolus of worms • Complete Blood Count: Eosinophilia • Histmines • Peroxidase

  16. Treatment • Mebendazole (Vermox): chewable tablet taken twice a day; minor side effects • Blocks of uptake of glucose and other nutrients • Pyrantelpamoate: combination of pyrantel and pamoic acid; sometimes paired with praziquantel • Paralysis of helminths • Albendazole: has not be approved; boradspectrum • Depletes their glycogen stores • No energy=death

  17. Prevention • We are making this a discussion, so put on those thinking hats!

  18. Prevention • Proper hygiene and sanitation: wash your hands!!!! • Wash produce properly before consuming • Bleach doesn’t work, iodine does! • Dispose feces away for habitations • This prevents contaminated food and water sources • Use a toilet • Eggs can live in the soil for 1-3 years

  19. Epidemiology • 1.5 billion infections in the world • Primarily in Africa and Asia • About 4 million of these are in the United States.

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