Giardia is a microscopic parasite that causes the diarrheal illness known as giardiasis. Giardia (also known as Giardia intestinalis, Giardia lamblia, or Giardia duodenalis) is found on surfaces or in soil, food, or water that has been contaminated with feces (poop) from infected humans or animals.
Giardia is protected by an outer shell that allows it to survive outside the body for long periods of time and makes it tolerant to chlorine disinfection. While the parasite can be spread in different ways, water (drinking water and recreational water) is the most common mode of transmission.
What is giardiasis? expanded
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, deer, and beavers) has been infected with Giardia, the parasite lives in the intestines and is passed in feces (poop). 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.
How do you get giardiasis and how is it spread? collapsed
Giardiasis can be spread by:
Swallowing Giardia picked up from surfaces (such as bathroom handles, changing tables, diaper pails, or toys) that contain feces (poop) from an infected person or animal
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
Eating uncooked food that contains Giardia organisms
Having contact with someone who is ill with giardiasis
Traveling to countries where giardiasis is common
Anything that comes into contact with feces (poop) from infected humans or animals can become contaminated with the Giardia parasite. People become infected when they swallow the parasite. It is not possible to become infected through contact with blood.
What are the symptoms of giardiasis? collapsed
Giardia infection can cause a variety of intestinal symptoms, which include:
Gas or flatulence
Greasy stool that can float
Stomach or abdominal cramps
Upset stomach or nausea
These symptoms may also lead to weight loss. Some people with Giardia infection have no symptoms at all.
How long after infection do symptoms appear? collapsed
Symptoms of giardiasis normally begin 1 to 3 weeks after becoming infected.
How long will symptoms last? collapsed
In otherwise healthy people, 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 at risk of getting giardiasis? collapsed
Though giardiasis is commonly thought of as a camping or backpacking-related disease and is sometimes called “Beaver Fever,” anyone can get giardiasis. People more likely to become infected include:
Children in childcare settings, especially diaper-aged children
Close contacts of people with giardiasis (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
People exposed to human feces (poop) through sexual contact
What should I do if I think I may have giardiasis? collapsed
Contact your healthcare provider.
How is giardiasis diagnosed? collapsed
Your healthcare provider will ask you to submit stool (poop) 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.
What is the treatment for giardiasis? collapsed
Many prescription drugs are available to treat giardiasis. Although the Giardia parasite 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 ill. 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.
My child does not have diarrhea, but was recently diagnosed as having a Giardia infection. My healthcare provider says treatment is not necessary. Is this correct? collapsed
Your child does not usually need treatment if he or she has no symptoms. However, there are a few exceptions. If your child does not have diarrhea, but does have other symptoms such as nausea or upset stomach, tiredness, weight loss, or a lack of hunger, you and your healthcare provider may need to think about treatment. The same is true if many family members are ill, or if a family member is pregnant and unable to take the most effective medications to treat Giardia. Contact your healthcare provider for specific treatment recommendations.
What can I do to prevent and control giardiasis? collapsed
To prevent and control infection with the Giardia parasite, it is important to:
Practice good hygiene
Avoid water (drinking or recreational) that may be contaminated
Avoid eating food that may be contaminated
Prevent contact and contamination with feces (poop) during sex
Can I get giardiasis from my pet? collapsed
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.
Illness & Symptoms
Giardiasis is the most frequently diagnosed intestinal parasitic disease in the United States and among travelers with chronic diarrhea. Signs and symptoms may vary and can last for 1 to 2 weeks or longer. In some cases, people infected with Giardia have no symptoms.
Acute symptoms include:
Greasy stools that tend to float
Stomach or abdominal cramps
Upset stomach or nausea/vomiting
Dehydration (loss of fluids)
Other, less common symptoms include itchy skin, hives, and swelling of the eye and joints. Sometimes, the symptoms of giardiasis might seem to resolve, only to come back again after several days or weeks. Giardiasis can cause weight loss and failure to absorb fat, lactose, vitamin A and vitamin B12.
In children, severe giardiasis might delay physical and mental growth, slow development, and cause malnutrition.