This is an egg of Ascaris lumbricoides. Ascarides are roundworms, a common parasitic infection throughout the world. It is estimated that as many as 1 billion people (one sixth of the world population) may be infected with roundworms.
Review Date 4/10/2020
Updated by: Michael M. Phillips, MD, Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.