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Additional Information From NIAID

Hookworm Disease

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The parasitic roundworm, known as hookworm, causes hookworm disease. Necator americanus is the most common type of hookworm that causes infection in the United States.

  • Hookworm eggs are passed in human feces onto the ground where they develop into infective larvae (immature worms).
  • When the soil is cool, the larvae crawl to the nearest moist area and extend their bodies into the air.
  • The larvae stay in the soil—waving their bodies to and fro—until they come into contact with human skin, usually when stepped on by a bare foot, or until they are driven back into the ground by the heat.

Last Updated September 13, 2007

Last Reviewed May 12, 2011