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What is Giardia? — Giardia is an infection of the digestive system (figure 1). The infection can cause diarrhea, nausea, and stomach ache. It is very common.
What are the symptoms of Giardia? — Giardia infections do not always cause symptoms. Some people carry the parasite that causes Giardia without ever knowing it. When symptoms do happen, they can include:
Diarrhea that comes on suddenly and that can start off watery
Feeling ill
Having bowel movements that are fatty and smell worse than usual
Belly cramps, gas, and bloating
Nausea or vomiting
Weight loss
Should I see a doctor or nurse? — It depends. See your doctor or nurse if you:
Have severe diarrhea, meaning it happens many times in a day
Have severe belly pain
Cannot eat or drink
Have a fever higher than 100.4°F (38°C)
Young children and older adults with symptoms should make sure to see their doctor or nurse. That's because these groups can get dehydrated more easily than other people.
How did I catch Giardia? — Giardia infections can spread in 3 ways:
From person to person – The parasite that causes Giardia lives in bowel movements of people who are infected. You can catch Giardia from another person if they do not wash their hands after a bowel movement and then touch you. The same is true for someone who changes a diaper on a child or an adult and then does not wash his or her hands. It is also possible to catch Giardia through any kind of anal sex (even if you use a condom).
Through food – The parasite that causes Giardia can live on food. Cooking kills it. But if food is not cooked or not handled the right way, it can carry Giardia.
Through water – The parasite that causes Giardia can live in water sources that people drink from. For instance, Giardia can live in streams or drinking wells. People who camp and hike are at risk of getting Giardia if they drink water from lakes or streams without treating the water properly first.
Is there a test for Giardia? — Yes. If your doctor or nurse thinks you might have Giardia, he or she will ask you for a bowel movement sample. At the lab, the sample can be checked for Giardia and other infections that can cause the same symptoms as Giardia.
How is Giardia treated? — Treatment for Giardia involves taking an antibiotic medicine for several days. In most cases, that gets rid of the infection and its symptoms. In some cases, though, Giardia does not get better with the first round of antibiotics. If that happens, doctors usually suggest changing the type or dose of antibiotic, or increasing the length of time a person is treated.
If you do not have symptoms of Giardia, you might not need antibiotics – even if your test shows you have the infection. Some people with Giardia can beat the infection without treatment. But children in daycare and people who work with food should be treated for Giardia, even if they have no symptoms. This helps prevent the spread of infection.
Can Giardia be prevented? — Yes, it can. The most important thing is to be clean. Follow these tips:
Wash your hands with soap and water after using the bathroom, and teach children to do the same
Wash your hands with soap and water after changing diapers or after touching anyone who can't control his or her bowels
Throw away dirty diapers right away in sealed trash bins
Wash clothes that could have even small amounts of bowel movement on them
Try not to swallow water when swimming
Kill the germs and parasites in your drinking water when traveling or hiking. You can do this by doing one of these things:
•Boiling drinking water for at least 10 minutes at a hard boil
•Adding 5 drops of tincture of iodine to 4 cups of water and waiting 30 minutes. Tincture of iodine is a liquid you can buy at most pharmacies or camping goods stores. People also use it on cuts to kill germs. It is much better at killing Giardia than bleach.
•Using a good water filtering system
All topics are updated as new evidence becomes available and our peer review process is complete.
This topic retrieved from UpToDate on: Mar 30, 2020.
Topic 15896 Version 6.0
Release: 28.2.2 - C28.105
© 2020 UpToDate, Inc. and/or its affiliates. All rights reserved.

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