ABSTRACT
A. lumbricoides is a nematode parasite infecting about 1 billion people worldwide. In the USA ascariasis is endemic in southeastern states and approximately 4 million people per year are infected with A. lumbricoides. The normal habitat for the adult worm is the jejunum. Infection is acquired by ingestion of embryonated eggs releasing the larvae, which pass through a pulmonary migratory phase en route to maturity. A. lumbricoides is the largest parasitic nematode of the gastrointestinal tract of humans. Male worms measure 15-31 cm, and females 20-25 cm. A. lumbricoides thrives in moist temperate regions where health-related behavior is known to influence its transmission and distribution.
