Giardia Symptoms and Treatment

Giardiasis (GEE-are-DYE-uh-sis) is a diarrheal illness caused by a microscopic parasite, Giardia intestinalis. The symptoms are intestinal and there are several drugs for treatment. Once a person or animal has been infected with Giardia, the parasite lives in the intestine and is passed in feces. Because the parasite is protected by an outer shell, it can survive outside the body and in the environment for long periods of time (i.e., months).

The Giardia parasite lives in the intestine of infected humans or animals (e.g., cats, dogs, cattle, deer, and beavers). Millions of germs can be released in a bowel movement of an infected human or animal. Giardia is found on surfaces or in soil, food, or water that has been contaminated with the feces from infected humans or animals. You can become infected after accidentally swallowing the parasite; you cannot become infected through contact with blood. Giardia can be spread by:

  • Accidentally swallowing Giardia picked up from surfaces (such as bathroom fixtures, changing tables, diaper pails, or toys) contaminated with feces from an infected person or animal.
  • Drinking water or using ice made from contaminated sources (e.g., lakes, streams, shallow [less than 50 feet] or poorly monitored or maintained wells).
  • Swallowing recreational water contaminated with Giardia. Recreational water includes water in swimming pools, water parks, hot tubs or spas, fountains, lakes, rivers, springs, ponds, or streams that can be contaminated with feces or sewage from humans or animals.
  • Eating uncooked food contaminated with Giardia.
  • Having contact with someone who is ill with giardiasis.
  • Traveling to countries where giardiasis is common and being exposed to the parasite as described in the bullets above.

Giardia infection can cause a variety of intestinal signs or symptoms, which include

  • Diarrhea
  • Gas or flatulence
  • Greasy stools that tend to float
  • Stomach or abdominal cramps
  • Upset stomach or nausea

These symptoms may lead to weight loss and dehydration. Some people with Giardia infection have no symptoms at all. Symptoms of giardiasis normally begin 1 to 2 weeks (average 7 days) after becoming infected.  In otherwise healthy persons, symptoms of giardiasis may last 2 to 6 weeks. Occasionally, symptoms last longer. Medications can help decrease the amount of time symptoms last.

Who is most likely to get giardiasis?

Anyone can get giardiasis. Persons more likely to become infected include

  • Children in child care settings, including diaper-aged children.
  • Close contacts (such as those in the same family or in the same household or child care setting) or caregivers of infected people.
  • People who drink water or use ice made from contaminated sources (e.g., lakes, streams, shallow or poorly monitored or maintained wells). Contaminated water may include water that has not been boiled, filtered, or disinfected with chemicals.
  • Backpackers, hikers, and campers who drink untreated or insufficiently treated water or who do not practice good hygiene (e.g., proper hand washing).
  • People who swallow contaminated water while swimming, especially in lakes, rivers, springs, ponds, and streams. Several community-wide outbreaks of giardiasis have been linked to recreational water or drinking water contaminated with Giardia.
  • International travelers.
  • People exposed to human feces through sexual contact.

If you think you have giardisis, contact your health care provider. Your health care provider will likely ask you to submit stool samples to check for the parasite. Because Giardia can be difficult to diagnose, your provider might ask you to submit multiple stool specimens collected over a few days.

Several prescription drugs are available to treat Giardia infection. Although Giardia can infect all people, young children and pregnant women might be more susceptible to dehydration resulting from diarrhea and should, therefore, drink plenty of fluids while ill. Rapid loss of fluids from diarrhea can be especially life threatening to infants. Therefore, parents should talk to their health care providers about fluid replacement therapy options for infants.

My child does not have diarrhea, but was recently diagnosed as having Giardia infection. My health care provider says treatment is not necessary. Is this true?

Treatment is generally not necessary when your child has no symptoms. However, there are a few exceptions. If your child does not have diarrhea, but does have other symptoms such as nausea, fatigue (feels very tired), weight loss, or a poor appetite, you and your health care provider may wish to consider treatment. The same is true if several family members are ill, or if a family member is pregnant and therefore not able to take the most effective anti-Giardia medications.

If my child or I have been diagnosed with giardiasis, should I worry about spreading the infection to others?

Yes, Giardia infection can be very contagious. Follow these guidelines to avoid spreading Giardia to others:

  1. Wash your hands with soap and water after using the toilet and before handling food.
  2. Do not swim in recreational water (pools, hot tubs, lakes, rivers, the ocean, etc.) while you have diarrhea and for 1 week after your diarrhea stops. You can pass Giardia in your feces and contaminate the water after your symptoms have stopped. This has resulted in outbreaks of Giardia infection among recreational water users.
  3. Avoid fecal exposure during sexual activity. This is especially important while experiencing diarrhea caused by giardiasis.
    • Use a barrier during oral-anal sex.
    • Wash hands immediately after handling a condom used during anal sex or after touching the anus or rectal area.

If your child is diagnosed with giardiasis, follow these guidelines to help your child avoid spreading Giardia infection to others:

  1. Wash your hands and your child’s hands after changing the child’s diapers or assisting your child with toileting.
  2. Do not allow your child to swim while he or she has diarrhea and for 1 week after your child’s diarrhea stops.

If your child receives child care with other children, work with the child care provider or your local health department to identify steps (e.g., keep your child out of group child care until the giardiasis symptoms resolve) you can take to help stop the other children from becoming infected with Giardia.