PRACTICAL PROJECT REPORT
LIFE CYCLE OF ASCARIS LUMBRICOIDES
B.Sc. Zoology Practical Project
Submitted By: ______________________
Roll No.: __________________________
Class: B.Sc. Semester _____________
1. Introduction
Ascaris lumbricoides is a parasitic roundworm belonging to the phylum Nematoda. It infects the small intestine of humans and is one of the most widespread soil‑transmitted helminths. The infection caused by this worm is known as ascariasis. Poor sanitation, contaminated food, and lack of hygiene are major reasons for its prevalence.
2. Objectives
1. To study the morphology of Ascaris lumbricoides.
2. To understand the complete life cycle.
3. To identify the stages of larval migration inside the human body.
4. To study the mode of infection and transmission.
5. To outline prevention and control measures.
3. Habitat
Ascaris lumbricoides inhabits the small intestine of human beings, where it feeds on digested food materials.
4. Morphology
Adult worms are cylindrical, elongated and tapering at both ends.
Colour: Creamy white or pinkish.
Male worm: Smaller (15–30 cm) with curved posterior end.
Female worm: Larger (20–40 cm) with straight posterior end.
Eggs:
Fertilized eggs: Round/oval with thick mammillated shell.
Unfertilized eggs: Elongated with thin shell.
5. Mode of Transmission
Ascaris spreads through the fecal‑oral route. Humans become infected by consuming food or water contaminated with embryonated eggs found in soil contaminated with human feces.
6. Complete Life Cycle of Ascaris lumbricoides
The life cycle is monoxenous (completed in a single host).
Stage 1: Egg Laying
Female lays up to 200,000 eggs per day in the intestine. Eggs are passed out with feces.
Stage 2: Development in Soil
Under warm, moist conditions eggs become embryonated and infective within 2–4 weeks.
Stage 3: Entry into Human Body
Infective eggs are swallowed with contaminated food or water.
Stage 4: Larval Hatching
Eggs hatch in the duodenum releasing L2 larvae which penetrate the intestinal wall.
Stage 5: Hepato‑Pulmonary Migration
Larvae travel: Intestine → Blood → Liver → Heart → Lungs.
Larvae grow in lungs, migrate to bronchi, trachea, pharynx, and are swallowed again.
Stage 6: Return to Intestine
Larvae mature into adults in the small intestine, completing the cycle.
7. Symptoms / Pathogenicity
1) Abdominal pain
2) Malnutrition and weight loss
3) Intestinal obstruction (severe cases)
4) Cough and breathing difficulty (lung migration)
5) Growth retardation in children
6) Allergic reactions
8. Prevention and Control
1. Maintain proper sanitation.
2. Wash hands before eating.
3. Avoid open defecation.
4. Wash vegetables and fruits properly.
5. Participate in routine deworming programs (Albendazole/Mebendazole).
Conclusion
Ascaris lumbricoides remains one of the most prevalent parasitic infections in developing countries. Understanding its life cycle is essential for breaking the transmission cycle. Improved hygiene, sanitation, and regular deworming are key to preventing ascariasis.
References
1. Chatterjee, K.D. Parasitology: Protozoology and Helminthology.
2. Park’s Textbook of Preventive and Social Medicine.
3. WHO – Soil Transmitted Helminths Fact Sheet.
4. CDC – Ascaris Infection Guidelines.
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