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Giardia Intestinalis Infections

Giardiasis is the name doctors give to infections caused by a microscopic parasite called Giardia Intestinalis. This organism may be found in the stools of an infected person. It can be transmitted by person-to-person contact in places like child care centers and among family members who have not properly washed their hands after using the bathroom or changing diapers. Giardia may also be present in contaminated food and water and is a risk for campers drinking untreated water from mountain streams, which can be contaminated by stool from infected animals and campers.

Signs and Symptoms

Most children with a Giardia infection have no symptoms at all. A few have abdominal pain and watery, foul-smelling diarrhea that can lead to dehydration. They may also have excessive gas and bloating and could have a poor appetite, leading to weight loss. Fever is uncommon. Most often, symptoms begin 7 to 14 days after exposure to the Giardia parasite and can last, without treatment, for about 4 to 6 weeks.

How Is the Diagnosis Made?

A stool sample from your child will be examined for the presence of Giardia Intestinalis.


To keep your child well hydrated, she should drink plenty of liquids recommended by your pediatrician, such as over-the-counter or homemade oral rehydrating solutions. Your doctor may also prescribe prescription medicines (most commonly, metronidazole, furazolidone, or nitazoxanide) that cure most cases after 5 to 7 days of treatment. ​If your child has Giardia organisms in the stool but does not have symptoms, no treatment is needed.


  • When a child attends a child care center, parents should make sure the staff members practice good hygiene and encourage children to wash their hands frequently with soap and water. 
  • Toys that a child puts in her mouth should be washed and disinfected before another youngster plays with them.
  • It is a good idea to wash and peel raw fruits and vegetables before they are eaten.
  • Children should avoid drinking untreated water from streams, lakes, rivers, and ponds. 
  • Take bottled water on camping trips or boil, filter, and treat your drinking water with chemical tablets before drinking it.

Last Updated
Adapted from Immunizations and Infectious Diseases: An Informed Parents Guide (Copyright © 2006 American Academy of Pediatrics) and updated 2011
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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