Parasitology Training Manual

Ascaris lumbricoides

• Abbreviation: Al
• Egg size(fertile): 45 - 85 microns
• Egg size(infertile): 78 - 105 microns
• Adult size(male): 10 - 31 cm
• Adult size(female): 22 - 35 cm
• They are large worms with a striated cuticle.
• Eggs should be considered infective as they can survive fixatives and chlorination.
• The adult male is generally shorter and possesses a curved posterior.

Click on the images below to enlarge

A. lumbricoides Life Cycle

Eggs are released by females in the small intestine of man. Non-infective eggs are passed in
feces, becoming infective in about 3 weeks. The now infective eggs are ingested by man.
Larva hatch in the small intestine, penetrate the intestinal wall and migrate via the blood
stream to the lungs(this occurs in 1 - 7 days). The larva now migrate into the trachea where
they are coughed up into the esophagus and are swallowed. Maturation takes place in the small
intestine in about 2 months. Click here for schematic diagram.

Return To Helminth Introduction

The material on this site is owned by Scientific Image and Consulting
David M. Raymondo
MLT, CLS(m)
Professional Affiliation: Gamma-Dynacare Medical Laboratories, Ottawa, Ontario, Canada
Gamma-Dynacare is a Division of the Dynacare Health Group