Round Worm Life Cycle in Humans

The roundworm is a parasitic nematode that infects the human intestines. According to buzzle.com, roundworms and their eggs and larvae are found in the soil and enter the human body most often when we touch the soil and then touch our mouths. According to the University of Maryland Medical Center, roundworm infections are more common in warm, tropical climates.

Eggs

• The female roundworm can produce roughly 200,000 eggs per day, some fertile, some not. The fertilized eggs embryonate and become infectious after about 18 days, depending on the temperature.

Larval Stage

• Some fertile eggs hatch into larvae before entering a person's body. After the larvae are swallowed, they feed and grow until they reach the molting process. The molting process occurs in four stages before the nematode reaches the adult stage.

Process

• The larvae invade the intestinal mucosa and circulate to the lungs, where they grow for 10 to 14 days. They then penetrate the alveolar walls, travel by way of the bronchial tree to the throat and are swallowed. When they reach the small intestine, they develop into adult worms.

Adult

• Adult worms live in the lumen of the small intestine. The adult male is 15 to 30 cm in length by 0.3 to 0.8 cm in diameter and has a curved tail. The adult female is 20 to 35 cm in length by 0.5 cm in diameter. Adult worms can live one to two years.

Reproduction

• At the final stage of the life cycle, genders are established and the adults are capable of sexual reproduction. The female can produce around 6 million eggs during her lifetime.

  The process from swallowing the eggs to having mature worms develop in the intestine takes between two and three months.