Mayo Clinic Health Manager
Get free personalized health guidance for you and your family.
Get StartedCauses
By Mayo Clinic staffThe ascaris parasite can be transmitted when infected human feces are mixed with soil. In many developing countries, human feces are used for fertilizer or poor sanitary facilities allow human waste to mix with local soil in yards, ditches and fields. The microscopic eggs require 10 to 14 days in soil at warm temperatures to become capable of infecting a new host, and can remain viable in the soil for a long time. The eggs infect their hosts when humans eat contaminated vegetables or fruit grown in that soil.
After you ingest ascaris eggs, they hatch in your intestine and the larvae migrate to your lungs. Eventually the larvae reach your throat, where you cough them up and then swallow them. They then enter your intestine, where they mature into adults and mate. Adult worms can live up to two years, and female worms can produce more than 200,000 eggs daily. About two months after you first ingest ascaris eggs, mature worms begin laying eggs in your intestine. You then expel those eggs in your feces. If those eggs are ingested by someone else, the ascaris life cycle begins again.