Diseases Caused by Helminths > Ascariasis

Causative Organism: Ascaris lumbricoides — a parasitic roundworm; belongs to phylum Nematoda; an endoparasite of the human small intestine.

Mode of Transmission: Ingestion of food or water contaminated with Ascaris eggs. Eggs hatch in the intestine; larvae migrate through body organs and eventually settle as adult worms in the digestive tract.

Symptoms:

• Gastrointestinal discomfort - nausea, vomiting, abdominal pain
• Fever
• Loss of appetite and weight loss
• Presence of live worms in faeces
• Pulmonary disorders - pneumonitis (inflammation of lung tissue)
• Eosinophilia (elevated eosinophil count in blood)
• Dizziness and anaemia

Diagnosis:

• Microscopic examination of stool to detect eggs

Treatment:

Prevention and Control:

• Avoid open defecation; use proper sanitation facilities
• Wash hands thoroughly after using the toilet
• Wash vegetables and fruits thoroughly before eating
• Avoid consuming raw vegetables in endemic areas
• Maintain personal hygiene at all times

1. Adult worms live in the intestine of the human host
2. Fertilised eggs are passed out through faeces into the environment
3. Eggs reach the soil; infective larvae develop within the eggs
4. Eggs contaminate food - ingested (swallowed) by humans
5. In the intestine, larvae enter the blood
6. Blood carries larvae to the Heart → Lungs → Trachea
7. From trachea, larvae move to Pharynx → Oesophagus
8. Finally reach the intestine again, where they mature into adult worms
9. Cycle repeats

Life cycle of Ascaris lumbricoides