Life cycle Ascaris Lumbricoides

Question 1

What is the classification of Ascaris Lumbricoides?

Answer 1

Extracellular Helminth in the category nematode or roundworm

Question 2

How is Ascaris Lumbricoides transmitted?

Answer 2

Feces

Question 3

What are the steps of the Ascaris Lumbricoides lifecycle outside of the human host?

Answer 3

1. Adult worms live in the lumen of the small intestine.
2. Female can produce approximately 200.000 eggs per day which are passed with the feces. The unfertilized eggs that may be ingested will not be infectious.
3. The larva that develops in fertilized eggs takes 18 days to several weeks depending on the environmental conditions. The optimal conditions are warm, moist and shaded soil. So Ascaris can survive outside of the host.
4. After the eggs with now larva stage 3 are swallowed by humans via contaminated food or water

Question 4

What are the lifecycle steps of Ascaris Lumbricoides lifecycle in the human host?

Answer 4

5. The larva hatch and invade the intestinal mucosa and are carried via the portal circulation and later the systemic circulation to the lungs.
6. The larva mature further in the lungs in 10-14 days. The not fully developed worms penetrate the alveolar walls and ascent via the bronchi tree to the throat through coughing. In the throat they are swallowed so they reenter the gastrointestinal tract. Upon reaching the small intestine they develop into adult worms. Within 2-3 months they are required from ingestion of the infective eggs to oviposition by the adult female worm. Adult worms can live for 1-2 years.

Question 5

What type of life cycle does Ascaris Lumbricoides have?

Answer 5

Direct life cycle

Human is definitive host

Question 6

What is the reservoir for Ascaris Lumbricoides?

Answer 6

Human
Pigs
Soil
Sometimes Monkeys and Apes

Question 7

What are the symptoms of Ascaris Lumbricoides infection?

Answer 7

Often asymptomatic regardless of the species of the worm. If symptoms do occur they can be light and include abdominal discomfort. Half of the infections can cause intestinal blockage and impair growth in children. Other symptoms such as coughing are due to migration of the worms through the body.

Question 8

Where is Ascaris Lumbricoides endemic?

Answer 8

Worldwide but the burden is highest in tropical and subtropical regions with inadequate sanitation. It’s rare in developed countries.

Question 9

How is Ascaris Lumbricoides diagnosed?

Answer 9

Identifying Ascaris eggs in a stool sample using microscopy. Concentration procedure is recommended as a light infection is hard to detect.