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Giardia infection
Giardia; G. duodenalis; G. intestinalis; Traveler's diarrhea - giardiasis
Giardia, or giardiasis, is an infection of the small intestine. A tiny parasite called Giardia lamblia causes it.
Causes
The giardia parasite lives in soil, food, and water. It may also be found on surfaces that have come into contact with animal or human waste.
You may become infected if you:
- Are exposed to a family member with giardiasis
- Drink water from lakes or streams where animals such as beavers and muskrats, or domestic animals such as sheep, have left their waste
- Eat raw or undercooked food that has been contaminated with the parasite
- Have direct person-to-person contact in daycare centers, long-term care homes, or nursing homes with people who are infected with the parasite
- Have unprotected anal sex
Travelers are at risk for giardiasis throughout the world. Campers and hikers are at risk if they drink untreated water from streams and lakes.
Symptoms
The time between becoming infected and symptoms is 7 to 14 days.
Diarrhea is the main symptom. Other symptoms include:
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Abdominal gas or
bloating
Bloating
Abdominal bloating is a condition in which the belly (abdomen) feels full and tight. Your belly may look swollen (distended).
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Headache
Headache
A headache is pain or discomfort in the head, scalp, or neck. Serious causes of headaches are rare. Most people with headaches can feel much better...
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Loss of appetite
Loss of appetite
A decreased appetite is when your desire to eat is reduced. The medical term for a loss of appetite is anorexia.
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Low-grade
fever
Fever
Fever is the temporary increase in the body's temperature in response to a disease or illness. A child has a fever when the temperature is at or abov...
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Nausea
Nausea
Nausea is feeling an urge to vomit. It is often called "being sick to your stomach. "Vomiting or throwing-up is forcing the contents of the stomach ...
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Some people who have had a giardia infection for a long time continue having symptoms, even after the infection is gone.
Exams and Tests
Tests that may be done include:
- Stool antigen test to check for giardia
-
Stool ova and parasites exam
Stool ova and parasites exam
Stool ova and parasites exam is a lab test to look for parasites or eggs (ova) in a stool sample. The parasites are associated with intestinal infec...
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String test
(rarely performed)
String test
A string test involves swallowing a string to obtain a sample from the upper part of the small intestine. The sample is then tested to look for inte...
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Treatment
If there are no symptoms or only mild symptoms, no treatment may be needed. Some infections go away on their own within a few weeks.
Medicines may be used for:
- Severe symptoms or symptoms that do not go away
- People who work in a daycare center or nursing home, to reduce the spread of disease
Antibiotic treatment is successful for most people. A change in the type of antibiotic will be tried if symptoms do not go away. Side effects from some of the medicines used to treat giardia are:
- Metallic taste in the mouth
- Nausea
- Severe reaction to alcohol
In most pregnant women, treatment should not start until after delivery. Some drugs used to treat the infection can be harmful to the unborn baby.
Possible Complications
These complications can occur:
-
Dehydration
(loss of water and other fluids in the body)
Dehydration
Dehydration occurs when your body does not have as much water and fluids as it should. Dehydration can be mild, moderate, or severe, based on how muc...
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Malabsorption
(inadequate absorption of nutrients from the intestinal tract)
Malabsorption
Malabsorption involves problems with the body's ability to take in nutrients from food.
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Weight loss
Weight loss
Unexplained weight loss is a decrease in body weight, when you did not try to lose the weight on your own. Many people gain and lose weight. Uninten...
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When to Contact a Medical Professional
Call your health care provider if:
- Diarrhea or other symptoms last for more than 14 days
-
You have
blood in your stool
Blood in your stool
Bloody stools often are a sign of a problem in the digestive tract. Blood in the stool may come from anywhere along your digestive tract from your m...
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Prevention
Purify all stream, pond, river, lake, or well water before drinking it. Use methods such as boiling, filtration, or iodine treatment.
Workers in daycare centers or institutions should use good handwashing and hygiene techniques when going from child to child or person to person.
Safer sexual practices may decrease the risk for getting or spreading giardiasis. People practicing anal sex should be especially careful.
Peel or wash fresh fruits and vegetables before eating them.
References
DuPont HL. Approach to the patient with suspected enteric infection. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 283.
Haines CF, Sears CL. Infectious enteritis and proctocolitis and bacterial food poisoning. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease . 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 110.
Nash TE, Hill DR. Giardiasis. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 351.
Semrad CE. Approach to the patient with diarrhea and malabsorption. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 140.
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Digestive system - illustration
The esophagus, stomach, large and small intestine, aided by the liver, gallbladder and pancreas convert the nutritive components of food into energy and break down the non-nutritive components into waste to be excreted.
Digestive system
illustration
-
Giardiasis - illustration
Giardiasis is an intestinal infection caused by a protozoan and is spread by contaminated water or contact with an infected person. People who are travelling or hiking should assume water sources are contaminated and either purify drinking water or drink bottled water. Healthcare or daycare workers should practice good hygiene when going from person to person. Unprotected anal sex can also transmit Giardiasis from an infected person to the partner.
Giardiasis
illustration
-
Institutional hygiene - illustration
Workers in daycare centers or institutions such as hospitals and eldercare should use good handwashing and hygienic techniques when going from child to child or patient to patient.
Institutional hygiene
illustration
-
Digestive system organs - illustration
The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.
Digestive system organs
illustration
-
Digestive system - illustration
The esophagus, stomach, large and small intestine, aided by the liver, gallbladder and pancreas convert the nutritive components of food into energy and break down the non-nutritive components into waste to be excreted.
Digestive system
illustration
-
Giardiasis - illustration
Giardiasis is an intestinal infection caused by a protozoan and is spread by contaminated water or contact with an infected person. People who are travelling or hiking should assume water sources are contaminated and either purify drinking water or drink bottled water. Healthcare or daycare workers should practice good hygiene when going from person to person. Unprotected anal sex can also transmit Giardiasis from an infected person to the partner.
Giardiasis
illustration
-
Institutional hygiene - illustration
Workers in daycare centers or institutions such as hospitals and eldercare should use good handwashing and hygienic techniques when going from child to child or patient to patient.
Institutional hygiene
illustration
-
Digestive system organs - illustration
The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.
Digestive system organs
illustration
Review Date: 3/13/2016
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
