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Ascaris lumbricoides
Ascaris lumbricoides
Ascaris lumbricoides is the giant roundworm of humans.
Ascariasis is a disease caused by Ascaris lumbricoides
Is the largest of the intestinal nematodes parasitizing humans. It is the most common worm found in human.
– Site of inhabitation:
small intestine
Route of infection:
by mouth
Life span of the adult:
about 1 year
This worm lives in the lumen of small intestine, feeding on the intestinal contents, where the fertilized female lays eggs.
An adult female can produce approximately 240,000 eggs per day, which are passed in feces. When passed, the eggs are unsegmented and require outside development of about three weeks until a motile embryo is formed within the egg.
After the ingestion of embryonated eggs in contaminated food or drink or from contaminated fingers, host digestive juices acts on the egg shell and liberate the larva into the small intestine. These larvae penetrate the intestinal mucosa and enter lymphatics and mesenteric vessels. They are carried by circulation to the liver, right heart and finally to the lungs where they penetrate the capillaries into the alveoli in which they molt twice and stay for 10-14days and then they are carried, or migrate, up the bronchioles, bronchi, and trachea to the epiglottis. When swallowed, the larvae pass down into the small intestine where they develop into adults. The time from the ingestion of embryonated eggs to oviposition by the females is about 60-75 days. The adult worms live for about one year.
Ascaris lumbricoides
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