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Giardia

What is Giardia?

Giardiasis is a diarrheal disease caused by the microscopic parasite Giardia. A parasite is an organism that feeds off of another to survive. 

Once a person or animal (for example, cats, dogs, cattle, beavers, etc.) has been infected with Giardia, the parasite lives in the intestines and is passed in feces.

Once outside the body, Giardia can sometimes survive for weeks or months. Giardia can be found within every region of the U.S. and around the world.

Anything that comes into Contact with feces from infected humans or animals can become contaminated with the Giardia parasite.

How is Giardia spread?

• Eating uncooked food that contains Giardia organisms
• Drinking water or using ice made from water sources where Giardia may live (for example, untreated or improperly treated water from lakes, streams, or wells)
• Swallowing water while swimming or playing in water where Giardia may live, especially in lakes, rivers, springs, ponds, and streams
• Swallowing Giardia picked up from surfaces (such as bathroom handles, changing tables, diaper pails, or toys) that contain stool from an infected person or animal
• Having contact with someone who is ill with giardiasis
• Traveling to countries where giardiasis is common

People become infected when they swallow the parasite. It is not possible to become infected through contact with blood.

What are the Intestinal symptoms of Giardia?

• Diarrhea
• Gas or flatulence
• Greasy stool that can float
• Stomach or abdominal cramps
• Upset stomach or nausea
• Dehydration
Symptoms of giardiasis generally begin by having 2 to 5 loose stools (poop) per day and progressively increasing fatigue.

Other, less common symptoms include fever, itchy skin, hives, and swelling of the eyes and joints.

Over time, giardiasis can also cause weight loss and keep the body from absorbing nutrients it needs, like fat, lactose, vitamin A, and vitamin B12.

Some people with Giardia infections have no symptoms at all.

Who has the greatest Risk of infection?

Anyone can become infected with Giardia.

People more likely to become infected include:

• Children in child care settings, especially diaper-aged children
• Close contacts (for example, people living in the same household) or people who care for those sick with giardiasis
• People who drink water or use ice made from places where Giardia may live (for example, untreated or improperly treated water from lakes, streams, or wells)
• Backpackers, hikers, and campers who drink unsafe water or who do not practice good hygiene (for example, proper handwashing)
• People who swallow water while swimming and playing in recreational water where Giardia may live, especially in lakes, rivers, springs, ponds, and streams
• International travelers

If you think you have giardiasis contact your healthcare provider.

diagnosing giardia infection

Your healthcare provider will ask you to submit stool samples to see if you are infected.

Because testing for giardiasis can be difficult, you may be asked to submit several stool specimens collected over several days.

Recommended Prevention

• Practice good hygiene
• Avoid eating food that may be contaminated
• Avoid water (drinking or recreational) that may be contaminated

can I get Giardia from my pet?

The risk of humans acquiring Giardia infection from dogs or cats is small.

The exact type of Giardia that infects humans is usually not the same type that infects dogs and cats.

1999 CDC/ Dr. Stan Erlandsen

More Information on Giardia Infection

Treating Giardia Infection

Many prescription drugs are available to treat giardiasis.

Although Giardia can infect all people, infants and pregnant women may be more likely to experience dehydration from the diarrhea caused by giardiasis.

To prevent dehydration, infants and pregnant women should drink a lot of fluids while sick.

Dehydration can be life-threatening for infants, so it is especially important that parents talk to their healthcare providers about treatment options for their infants.

Diagnosis and Treatment

Talk to your doctor if you think you may be infected with Giardia.

Diagnosis Many kinds of germs can cause diarrhea. Knowing which germ is causing an illness helps your doctor decide what treatment to give you.

Healthcare providers can order laboratory tests to identify Giardia germs in the stool (poop) of someone who is sick. Sometimes it can be difficult for doctors to know for sure if Giardia is making you sick. This is because people with a Giardia infection do not pass Giardia germs with every stool. Even when there are Giardia germs in their stool, there may not be enough for the laboratory to find and identify them.

Because it can be difficult to detect Giardia, you may be asked to submit several stool samples collected over several days to see if you are infected.

Treatment If you have diarrhea, drink a lot of fluids while sick to avoid dehydration (loss of fluids).

Infants and pregnant women may be more likely to become dehydrated from diarrhea caused by a Giardia infection. Dehydration can be life-threatening for infants, so it is especially important to talk to a doctor about treatment options if your infant is sick.

Discuss treatment options with your doctor Many prescription drugs are available to treat Giardia infections. Because Giardia infections can be hard to diagnose, doctors often treat patients for Giardia if their history and symptoms suggest they have an infection. Medical history, nutrition, and whether patients have a weakened immune system affect how well prescription drugs work. Therefore, it is important for you to discuss treatment options with your doctor.