Ascaris has a (monogenetic) single host life cycle. Egg containing second juvenile are called embryonated eggs. These are infective to human host. In suitable conditions of temperature and moisture, these survive for 5 to 6 years in soil. People acquire infection by ingesting embryonated eggs with contaminated food and water. In the intestine of human host, the protective covering of ingested eggs are digested and 0.25 to 0.3 mm long juveniles become free in intestine lumen.