1. Ascaris lumbricoides
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: Adult worms: Humans 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…
is-bad-Ascaris-lumbricoides

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 Ascaris lumbricoides 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
Pyrantel pamoate: 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

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

19. 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

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