What is giardiasis?
Commonly called giardia, giardiasis is an intestinal infection caused by the protozoan Giardia lamblia.
What are the symptoms of giardia?
Symptoms of giardia infection are diarrhea, abdominal cramps, pale and greasy stools, fatigue, bloating, and weight loss. Diarrhea may last for days or weeks, or may come and go. Symptoms vary from person to person. Some people with giardia have no symptoms at all. Symptoms usually start from five to 25 days after swallowing the cyst.
How do people get giardia?
People and animals infected with giardia pass it in their stool. People become infected:
- directly by hand-to-mouth transfer from the stool of an infected person. That is, hands can be soiled when using the toilet. If hands are not thoroughly washed, the giardia can be transferred to food, drink or items handled or eaten by another person.
- indirectly by swallowing water that has been contaminated with stool that contains giardia (when swimming in ponds, drinking from streams, etc.).
- What are common sources of giardia?
- drinking contaminated water from streams, rivers, springs and ponds
- infected household and day care contacts, especially children in diapers (See Giardiasis in Day Care Centers, also available from the Health Department.)
- swimming in untreated surface water, such as wading pools, ponds, rivers, streams or lakes
- private water systems (wells or springs) that are not correctly installed or maintained
What tests are available for diagnosing giardia?
Giardia is diagnosed by a laboratory test that examines a stool sample for Giardia lamblia cysts or antigen. Depending on the type of test that is done, more than one stool sample may be necessary. In that case, specimens should be collected at least 48 hours apart.
Should all household members be tested when a person has giardia?
Often more than one person in a household is infected. When one person tests positive for giardia, it is important to identify other infected household members. By identifying and treating all infections within the household, the possibility of reinfection is reduced. Household members who do not have diarrhea should be tested since infection can be present without diarrhea. Household members who have diarrhea should be referred to their physician for diagnosis and treatment.
Household members who work in jobs where giardia infection could easily be spread must be tested. Examples:
- Food handlers - cooks, wait staff, food or dairy processing plant workers
- Anyone who has personal contact with patients
- Child care providers who prepare food or bottles, or feed children
The Vermont Department of Health also recommends that household members who attend day care be tested. (See facts sheets on Giardiasis in High Risk Occupations and Giardiasis in Day Care Centers, also available from the Health Department.)
Is giardia preventable?
Thorough hand washing with warm running water and soap reduces the risk of spreading giardia from an infected person to others. Always wash hands after using the bathroom or diapering a baby, and before touching food.
When a household member has giardia, carefully clean and disinfect areas that could be contaminated with cysts, including bathrooms, clothing soiled with stool, etc.
Do not prepare food for people outside your household when infected with giardia.
Do not drink untreated surface water.
If your drinking water comes from a private well or spring, have the water tested for bacterial contamination. If results show the presence of coliform bacteria contact the Health Department for information about improving your drinking water supply. (The Health Department Laboratory doesn’t test for giardia, however, bacterial testing will indicate the presence of human or animal waste. Test kits are available by calling 1-800-660-9997 or 802-863-7335.)
If you suspect that your water supply is a source of giardia, boiling the water for five minutes will kill the parasite. Boil all drinking water, including water used for juices, coffee, ice cubes, tooth brushing, etc.
How is giardia treated?
People with symptoms of giardia should see a physician for diagnosis and treatment. There are prescription medications that will eliminate this infection. If you think that you or a family member might have giardia, contact your health care providers.
The Vermont Department of Health
Division of Epidemiology and Disease Prevention
P.O. Box 70, Burlington, VT 05402
863-7240 or 1-800-640-4374 toll-free