Life Cycle of Ascaris

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Questions and Answers

What is the primary mode of transmission of hookworm to humans?

By inhaling airborne larvae

Via penetration of the skin by filariform larvae (correct)

By ingesting infected eggs

Through contaminated food and water

Where do the adult hookworms mature within the human body?

Stomach

Small intestine (correct)

Large intestine

Colon

Which symptom is commonly associated with a light hookworm burden in humans?

Severe abdominal pain

Respiratory distress

Allergic itching at the site of larval penetration (correct)

Bloody diarrhea

How do hookworm larvae enter the human body after penetrating the skin?

Through the lymphatics and blood system to the lungs Signup and view all the answers

What happens to the eggs passed by adult female hookworms in the human body?

They are deposited into the intestine and eliminated in feces Signup and view all the answers

Under what conditions do first-stage rhabditiform larvae emerge from hookworm eggs?

In warm, moist soil Signup and view all the answers

How do Ascaris larvae travel from the small intestine to the lung?

Migrate through the bloodstream Signup and view all the answers

What is the role of the thick egg shell of Ascaris eggs?

Protects the eggs from environmental changes Signup and view all the answers

How long can Ascaris eggs remain infective when protected from sunlight and desiccation?

5 years Signup and view all the answers

What is the approximate lifespan of adult Ascaris worms?

1 year Signup and view all the answers

Where do adult Ascaris worms primarily live within the human body?

Small intestine Signup and view all the answers

What happens to Ascaris larvae after they are coughed up from the lungs to the pharynx?

They are swallowed and return to the intestine Signup and view all the answers

What is the impact of Enterobius vermicularis infection on human health?

Intense itching and inflammation of the anal and/or vaginal areas Signup and view all the answers

How do gravid females of intestinal nematodes like Enterobius vermicularis contribute to transmission?

By migrating to the perianal area at night to lay eggs Signup and view all the answers

Why are Enterobius vermicularis eggs rarely found in fecal samples?

Because they are released externally to the intestines Signup and view all the answers

Which statement best describes the life cycle of intestinal nematodes like Enterobius vermicularis?

Gravid females migrate to lay eggs outside the intestines Signup and view all the answers

How do viable nematode eggs contribute to the persistence of infection?

By surviving for extended periods in cool, moist environments Signup and view all the answers

Which factor makes Enterobiasis more likely to go undetected?

Mild nausea and vomiting Signup and view all the answers

Study Notes

Hookworm Infection

Hookworms are classified into two species: Ancylostoma duodenale (found in Europe and South America) and Necator americanus (found in North America and Africa)
Hookworms are transmitted through soil, where larvae penetrate the skin
Larvae migrate to the lymphatics and blood system, eventually reaching the lungs, where they penetrate the capillaries and enter the alveoli
Larvae continue to develop in the bronchioles, are coughed up to the pharynx, swallowed, and deposited into the intestine
Maturation of larvae into adult hookworms occurs in the intestine
Adult females lay 10,000 to 20,000 eggs/day, which are passed into the outside environment via feces
Eggs develop into first-stage rhabditiform larvae within 24 to 48 hours in warm, moist soil

Clinical Manifestation

Asymptomatic hookworm infection: patients with a light hookworm burden may not exhibit clinical symptoms
Hookworm disease may cause severe allergic itching at the site of penetration, sore throat, and/or bloody sputum
Repeated infections can lead to cutaneous larva migrans, a skin condition characterized by intense itching and inflammation

Life Cycle

Eggs hatch in the small intestine, and larvae penetrate the intestine wall, enter the bloodstream, and migrate to the liver
Larvae travel to the lung via the bloodstream, break out of lung capillaries into alveoli, and are coughed up to the pharynx
Larvae are swallowed and return to the intestine, where they mature into adults
Adult hookworms have a lifespan of approximately 1 year

Intestinal Nematodes

Enterobius vermicularis (pinworm) life cycle:
- Eggs are ingested, hatch in intestine, larvae mature, and adults live in the colon
- Gravid females migrate to the perianal area at night to lay eggs
- Eggs develop to the infective stage within 4-6 hours and can survive for extended periods in cool, moist environments
Trichuris trichiura, Ascaris lumbricoides, Necator americanus, and Ancylostoma duodenale are other intestinal nematodes mentioned

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Description

Learn about the life cycle of Ascaris, a type of parasitic worm that infects the human body. From hatching in the small intestine to maturing into adults, follow the different stages of development.