Transmission
Almost more than any other parasitic disease, inadequate personal hygiene leads to Ascaris infection. Human feces found in fields, streets, and back yards are a major source of infective eggs in heavily populated areas.
The eggs do not infect humans when first excreted by the roundworm. They usually are transmitted by hand to mouth. The use of human feces as fertilizer may also permit transmission of infective eggs through food that is grown in the soil and eaten without being thoroughly washed. The eggs are resistant to extremes of temperature and humidity.
The eggs require several weeks to develop and become infective. If you swallow infective eggs, they pass into your intestines where they hatch into larvae and then begin their journey through your body. Once through your intestinal wall, the eggs reach your lungs by means of the bloodstream or lymphatic system.
- In your lungs, they pass through the air sacs, are carried up the bronchial tree with respiratory secretions and into your throat.
- When in your throat, you re-swallow them, and they return to the small intestine where they grow, mature, and mate.
The worms become mature in about two months.