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Ascaris lumbricoides

Ascaris lumbricoides. Kelsey and Emily. Taxonomy. Kingdome: Animalia Phylum: Nematode Class: Rhabditea Order: Ascaridida Family: Ascarididae Genus: Ascaris Species: lumbricoides - A. lumbricoides infects humans -largest intestinal roundworm

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Ascaris lumbricoides

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  1. Ascaris lumbricoides Kelsey and Emily

  2. Taxonomy • Kingdome: Animalia • Phylum: Nematode • Class: Rhabditea • Order: Ascaridida • Family: Ascarididae • Genus: Ascaris • Species: lumbricoides • -A. lumbricoides infects humans • -largest intestinal roundworm • -most common human helminth infection • -A. Suum is a relative that infects pigs

  3. Geographical Distribution • -World Wide • -More common in humid, warm climates • -temperate regions • -uncommon in the U.S. • -does occur in rural S.E. United States

  4. Morphology • Eggs • -fertilized and unfertilized are passed in feces • -eggs are extremely resistant • Unfertilized Fertilized • Larger and longer Round and have a thick shell

  5. Morphology • Larvae • Larvae in egg Larvae in lung sample

  6. Morphology • Adult worm • -Female: 20-35 cm • vulva is about 1/3 from anterior end • prominent lips • -Male: 15-30 cm • spicule and curved tail

  7. Life Cycle

  8. Step One -Adult worms are in small intestines -The female produces eggs (both fertelized and unfertelized) which are passed in the feces

  9. Step Two and Three • -Unfertilized eggs may be ingested, but are not infective • -Fertile eggs embryonate and become infective after 18 days or several weeks (depending on environmental factors)

  10. Step Four and Five -Infective eggs (J3/L3) are swallowed and larvae hatch in duodenum -Larvae invade intestinal mucosa to begin their migration stage.

  11. Step Six and Seven • -Larvae are carried to the lungs via the systemic veins. During their voyage they continue maturation • -Larvae mature in the lungs (J4/L4) and then penetrate alveolar walls and migrate up to the esophagus where they are swallowed once again.

  12. Step One again • -Larvae travel to the intestines where they mature to adult worms. • -Whole process takes about 2-3 months • -adult worms live 1-2 years

  13. Pathogenesis • Disease is called Ascariasis (adult worm) • -most people show no symptoms • -Light infections cause • abdominal discomfort • -heavy infections cause intestinal blockage, and impaired growth in children (malnourishment) Intestinal obstruction

  14. Pathogenesis • -Ascaris pneumonitis • -when larvae is leaving lung capillaries, it causes a small hemorrhage. This causes a poolage of blood and edema which clogs air spaces. This leads to parts of lungs becoming diseased or open to bacterial infections • -Migrating worms can get ‘lost’ and end up in other organs and may start and inflammatory response

  15. Transmission/Diagnosis • Transmission = Fecal/oral • -eggs can be found in soil or on fruits/veggies • Diagnosis = stool samples (looking for eggs) • -adult worms can be passed in stool or through nose/mouth • Treatment = albendazole and mebendazole (1-3 days) • -Warm milk and other home remedies

  16. Epidemiology • -This is a very common in developing counties (lack of bathrooms) • -Children are the most likely to get infected (lack of hygiene) • -the egg resistance contributes to the success of the parasite

  17. Control • -Sanitation (proper bathrooms) • -washing hands before handling food • -washing fruits and veggies (especially if they have been grown in manure)

  18. Possible Videos • http://www.youtube.com/watch?v=DxL2qHBetvI&feature=related • http://www.youtube.com/watch?v=FW76UxudEMk • http://youtu.be/HOaZCkA8Zvk

  19. Review • -Can you become infected by an unfertilized egg? • -How many lips does the A. lumbricoides have on its anterior end? • -True or False: when the juvenile worm is initially ingested it turns into the adult in the intestines. • -What two diseases does Ascaris cause? (hint: one is in the lungs) • -How do you diagnose these worms?

  20. Sources • http://www.cdc.gov/parasites/ascariasis/ • http://www.dpd.cdc.gov/dpdx/html/Ascariasis.htm • https://www.msu.edu/course/zol/316/alumtax.htm • Foundations of Parasitology: 7thedition

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